Research was done primarily using Anthony C. Yu’s 4 volume translation of Journey to the West, and the translation found on InnerJourneyToTheWest.com.
Please note that the sizes given in translations to Journey to the West can vary. Being a book from 1500s China, Journey to the West doesn’t use western units of measurement, instead using units such as li. But most western readers wouldn’t have a point of reference for these units, so English translations understandably replaced them with familiar ones such as miles.
To the credit of the translators, they usually got a decent approximation of the distances used, but this has created a few inconsistencies across translations. We’ve done our best to factor in these inconsistencies.
Also, some of the names differ a bit depending on the translation, but most of the quotes cited should have enough context to make sense.
Additional research into the cosmology of Buddhism and how it relates to Journey to the West, was done using JourneytotheWestResearch.com, MC Owen’s introductory lecture on Buddhist cosmology, and Adjahn Sona’s breakdown of Buddhist cosmology.
Finally, I will stress that I am not a Buddhist, and certainly not an authority on Buddhism. This research was done strictly to get a better understanding of Sun Wukong as a character, his abilities, and the role Buddhism’s cosmology plays in Journey to the West. Buddhism is a widely practiced religion, with many different sects and unique beliefs. If there is anything I get wrong about the general concept, I apologize.
Height: Under 4’0
Age: Around 1100 years old
Long ago, atop Flower Fruit Mountain, there was a large stone that had been receiving the essences of the sun and moon since the dawn of creation. One day, that large stone cracked and from it emerged a stone egg. And from that egg emerged a stone monkey. Upon birth, the monkey bowed to the 4 cardinal directions. Then, perhaps as a foretelling of what was to come, shot beams from his eyes all the way up to the Jade Emperor in Heaven.
This monkey quickly befriended other chimpanzees across the mountain, until their adventures brought them to a waterfall. Seeking to prove his courage, the monkey jumped through the ‘water curtain’ and behind it found a cave with an iron bridge leading to a beautiful sanctuary. Because of the prosperous new home the monkey had found for his friends, he gave himself the title of ‘Handsome Monkey King’. The king lived happily with his monkey companions for several hundred years, but became worried about his lengthy but finite lifespan.
So, he ventured across the continent of Jambudvipa to seek teachings. At a Taoist temple, he was taught The Way by Patriarch Puti Zushi, and through some very specific Chinese word-play, was given the name Sun Wukong (‘Monkey Wake to the Void’). Wukong quickly mastered the Art of the Earthly Multitude including flight, immortality, and many other mystical abilities. But after showing off his newfound abilities, Zushi told him to leave, and never mention who taught him his magic.
Wukong obliged and returned to Flower Fruit Mountain just in time to fight a demon who had been causing trouble for all the other monkeys. After a victorious battle, Wukong began acting as the Monkey King once again, amassing an army of fully armed chimpanzees numbering 47,000. But Wukong wanted a weapon of his own too. So, he barged into the palace of the Dragon King demanding one. Wukong went through the Dragon King’s entire arsenal, but none suited him. Until it was recommended he take one of the pillars in the palace: The Ruyi Jingu Bang. Which conveniently changed its size and form into a staff to perfectly suit Wukong.
Monkey King had his weapon, but for his arrogance in demanding it from the Dragon King, the demons of The Land of Darkness tried to take his soul. This wasn’t an issue for him though. Wukong just started beating up everyone in The Land of Darkness until he was allowed to leave. But not before crossing out his and several of his fellow monkeys’ names in the records of death.
The Jade Emperor and all the other immortals in Heaven were getting fed up with Wukong’s antics. Hoping to keep him in check, they offered him a position in Heaven as a glorified stable boy. Wukong accepted it, thinking it was a high honor. But when someone told him it was the lowest position in all of Heaven, Monkey became indignant, returned to Flower Fruit Mountain, and would only return to Heaven if he was given the title of Great Sage Equal to Heaven.
Before the conflict could escalate even more, the Jade Emperor appeased Wukong by giving him the hollow title, and changing his position. This time, Wukong was to be the protector of the Garden of Immortal Peaches. Naturally, Wukong ate most of the peaches, immobilized the garden’s attendants, got drunk, and downed 5 gourds of Laozi’s Pills of Immortality for good measure. When Wukong sobered up, he realized how much trouble he was in and fled to Flower Fruit Mountain yet again, this time in full preparation for war.
A war he inevitably fought, duking it out with Erlang, Prince Nezha, 100,000 Celestial Warriors, the 28 Constellations, and everything else Heaven could throw at him. Wukong fought through many of Heaven’s best warriors, but was ultimately subdued when Laozi threw a jade diamond armlet at him. Despite his capture, the heavenly immortals were unable to execute Wukong with any of the weapons or magic they had. Even after boiling him in Laozi’s 8 Trigram’s Furnace for 49 days, Wukong emerged stronger than ever. With no other options, the Jade Emperor went to the Buddha for help.
Buddha then made a deal with Wukong: If he could escape from the Buddha’s hand in one leap, the Heavenly Palace would be relinquished to him. Wukong agreed, and leapt to the very edge of Heaven, seeing 5 large pillars that marked its edge, which Wukong vandalized and urinated on.
Wukong leapt back to the Heavenly Palace, and demanded Buddha hold up his end of the deal. But as it turned out, Wukong never left Buddha’s palm. Because Buddha is the enlightened and transcendent one, he literally holds all things and existence within his hand. As evident in the graffiti and stench of urine that was now on his hand. The same graffiti and urine Wukong vandalized the pillars (or rather Buddha’s fingers) at the edge of Heaven with moments ago. Utterly defeated, Wukong saw the Buddha’s palm close on him, as he was sealed beneath the Five Phases Mountain as punishment.
500 years later, the Bodhisattva Guanyin gave Wukong a visit. She had been instructed by the Buddha to find a Buddhist practitioner worthy of taking a pilgrimage to Vulture Peak, retrieving scrolls with Buddha’s teachings, and bringing Buddhism to the land of China. She chose the Chinese monk Tansang Zang, AKA Tripitaka, for the job which he graciously accepted.
But to make the journey he would need Wukong’s protection. Wukong agreed to take the pilgrimage with Tansang Zang in exchange for his freedom. Once Tansang removed the seal at the top of Five Phases Mountain, and Wukong promptly destroyed the mountain he was imprisoned beneath, they were ready for their journey to the west.
Along the way they recruited further help from Zhu Bajie, AKA Pigsy, and Sha Wujing, AKA Friar Sandy. To keep Monkey in check, Tansang was given a magic circlet, which Monkey could not remove from his forehead that would tighten and cause him immense pain if Tansang ever recited a chant.
Monkey did abandon the journey a couple times, usually due to infighting. But he would always return to see his allies through a long, looooong journey. They encountered demons, enemy monks, heavenly enemies turned friends, silly shenanigans, and countless hardships. Through it all, they reached Vulture Peak, entered the Thunder Monastery, and were given the scrolls of Buddha’s teachings… Which ended up being completely blank.
Truly, Tansang Zang and his group’s journey was just as much about bringing enlightenment to China, as it was about bringing enlightenment to themselves. The kind of enlightenment where they could look at a blank sheet of paper and within it, see the same wisdom found within the Buddhist teachings. Still, the group couldn’t exactly return to China empty handed, so they went back to the Thunder Monastery, gave Buddha a gift, and got scrolls with actual words and teachings too.
The group returned from their 14 year pilgrimage, much much more quickly, and for their deeds were given honorary places in Heaven. Tansang Zang ascended to Buddhahood as the Candana-Punya Buddha. Pigsy was given the position as Heaven’s altar cleaner, where he would be given all the food he could eat. Sandy became the Golden Arhat. And Monkey, for protecting Tansang Zang, overcoming his impulsivity, and winning glory by defeating monsters and demons, was freed from his circlet, and ascended to become the Victorious Fighting Buddha.
Important things about Journey to the West’s world…
There has been some debate in various VS. circles over whether or not Buddhism’s cosmology should be used for something like Journey to the West. Journey to the West is in a weird position where it clearly borrows a ton of concepts from Buddhist cosmology, but isn't explicitly a part of Buddhist canon and does have differences.
The key difference is it also uses an assortment of gods, historical figures, and some cosmological concepts from Confucianism and Taoism. Most of these Chinese figures are also the primary occupants of Heaven. The Jade Emperor, Laozi, ETC. Who, obviously, aren't seen anywhere in traditional Buddhism. It would be like if someone wrote a story about a bunch of Norse gods hanging out on Olympus.
That said, while it is important to remember that Journey to the West is not a traditional Buddhist text, it simply borrows too much and directly references too many of the same concepts and structures from Buddhism for it to be ignored. Some of the more obvious examples are…
-The world being divided into 4 continents or 'Dvipa': Uttarakuru, Jambudvīpa, Pūrvavideha, and Aparagodaniya. (Chapter 28)
-Alluding to the Trāyastriṃśa’s existence as a Heavenly Realm by referencing 33 mansions within one of the heavenly planes (note: Trāyastriṃśa is the home of 33 devas in traditional Hinduism and Buddhism). (Chapter 4)
-Locations such as Mount Sumeru, which is the central axis to the world system in Buddhist and Hindu cosmology containing holy significance. (Chapter 21)
Put simply, it doesn’t make sense for the book to not be using the cosmology of the religion it’s themed around. This will be important for one of the feats later on.
With a lifespan of centuries, and one of the most notorious lengthy adventures in fiction, Wukong has the experience to back it.
-Wukong spent between 6 and 7 years learning language and etiquette from a Taoist Master (Chapter 2)
-Wukong is exceptionally gifted and a fast learner, having mastered magic very quickly while at the Patriarch Puti Zushi’s temple. (Chapter 2)
-He spent some time practicing and mastering unarmed combat, presumably while under Puti Zushi’s instruction. (Chapter 3) The style he uses is not specified, but in his fight with Rhinoceros King, he uses moves that are practiced in martial arts to this day. (Chapter 51)
-He also mastered warfare, and amassed an army of 47,000 monkeys (Chapter 3)
-With the magical abilities and martial prowess Wukong has gained, he is capable of fighting even hundreds of demons at once. (Chapter 31)
-As well as matching or surpassing demons and heavenly entities, many of whom have hundreds of years of combat experience. (Chapter 71)
-While very impulsive at times, Wukong is capable of being perceptive and clever as well. Such as when he used a clone of himself to defeat Nata (AKA Nezha) (Chapter 3), took down a foe by transforming into a piece of food, getting eaten, and attacking them from the inside (Chapter 66), and when he could tell that his tea was poisoned by the sight of 2 jujubes. (Chapter 73)
-In total, Wukong’s journey took 14 years. Over the course of it he encountered a variety of different demons, spirits, and other foes as he and his companions completed 81 ordeals (Chapter 98) (Chapter 99).
Ruyi Jingu Bang: Wukong’s iconic staff. It’s a divine weapon (Chapter 7) composed of a rare iron, emits a holy light (Chapter 3), weighs 13,500 catties (around 17,500 lbs) (Chapter 3), and can shift its size and thickness. It can be small and thin enough to fit into Wukong’s ear (Chapter 3), large enough to reach the Heavens and the Underworld (Chapter 3), and can duplicate itself into thousands or even tens of thousands of individual staffs. (Chapter 3) (Chapter 50)
While normally taking the form of a staff, through Wukong’s magic, the weapon can transform into just about anything Wukong wants. He once turned the staff into a steel file, and used it to escape some bonds. (Chapter 34)
Dragon King Treasures: Besides his staff, Wukong was also given a Golden Cuirass, a Feather Cap, and Cloud Walking Shoes by the Dragon King. Contrary to its name, Wukong does not need the Cloud Walking Shoes to move on and use clouds. In fact, there are no known supernatural powers these items possess, but the cuirass should presumably provide some decent protection. (Chapter 3)
It’s worth noting, Wukong no longer had these items after being imprisoned by Buddha, instead wearing the pelt of a tiger he killed throughout most of his journey. (Chapter 14)
Wind-Fixing Pill: A special pill given to Wukong by Lingji that makes whoever takes it unaffected by winds (Chapter 59). Even powerful winds from Princess Ironfan’s fan cannot affect Wukong after taking this pill (Chapter 59). It’s unknown if this effect was permanent, as we don’t see this immunity come up at any other point. But given other mystical pills in Journey to the West, such as the pills of immortality, were permanent, this one likely was too.
Life-Saving Hairs: 3 special hairs on Wukong that he received from the Boddhisatva. (Chapter 75) The only thing distinguishing them from his normal hairs is they are hard as iron, and presumably can perform magic his normal hairs cannot. For example, when Wukong was sealed in a vase, he used the hairs to create tools that allowed him to escape. (Chapter 75)
All prior attempts at trying to escape were met with failure, as whenever Wukong grew or shrunk himself, the vase grew and shrunk with him. (Chapter 75) Wukong had also shown difficulty escaping from other sealing objects in prior chapters, but he should be able to circumvent forms of sealing with these hairs. He puts the life-saving hairs back into his body after using them. So he should theoretically be able to use them a second time. (Chapter 75)
Unfortunately, this is the only instance where he uses the life-saving hairs, so it’s unknown what else they can do that his ordinary hairs cannot.
Sleep Insects: Special insects that put anything to sleep once they… Go up the target’s nose. Wukong won several of them from one of the 4 Heavenly Kings, Lokapāla. (Chapter 77) In the cited chapter, Wukong uses up most of the insects he had, but he kept 2 for breeding, so he should still have access to them.
He honestly shouldn’t have even needed to keep 2 because he demonstrates the ability to make these insects via transformation magic both before and after the above mentioned chapter. (Chapter 5) (Chapter 84) Which brings into question why he had to win the insects from Lokapāla in the first place. Regardless, through his transformation ability, Wukong can make hundreds of these insects. Enough to put a horde of demons to sleep. (Chapter 86)
Beyond superhuman strength, speed, and durability, Sun Wukong has…
Immortality: Possibly what Wukong is most infamous for because he has so many variants of it. Going through every known source of immortality he gains over his journey…
After mastering The Way thanks to his Taoist teacher, Wukong’s already extended lifespan was made indefinite, giving him ‘the age of Heaven’, along with some impressive resistances. (Chapter 2)
After fighting his way through the Region of Darkness, Wukong crossed his name, and the name of several of his monkey friends, out of the records of death. (Chapter 3)
He ate most of the peaches in the Garden of Immortal Peaches. (Chapter 5) The 3 variants in the garden offer 3 different types of immortality.
Lastly, he downed 5 gourds’ worth of Laozi’s immortality elixir. (Chapter 5)
Needless to say, Wukong isn’t aging any time soon. None of this means he can’t be killed under any circumstances, but it could prove difficult for many. Because Wukong’s name literally does not exist within the Ledger of Death anymore, it could also be argued he has some resistance to death curses (though this point is largely speculative).
Invulnerability & Elemental Resistance: Because of his immortality, Wukong is exceptionally tough, and invulnerable to most traditional forms of damage. He’ll regularly take direct blows from the bladed edged weapons of demons without a scratch. (Chapter 34) Even Heaven’s best weapons, and heavenly lightning and fire could not so much as char a hair on Wukong’s body. (Chapter 7) (Chapter 35)
However, there are workarounds to these resistances. Red Boy’s fire of Samadhi was able to harm Wukong (Chapter 41). This is presumably because it’s neither ordinary nor heavenly fire, and ignores conventional resistances. (Chapter 41) This is further backed up by the fact that the fire of Samadhi actually spreads when it comes in contact with water, rather than get put out. (Chapter 41)
Disease Immunity: Wukong’s learning of The Way has made it so he cannot get sick from diseases. (Chapter 2) Though more intense poisons appear to still take an effect (we’ll get to that later).
Shapeshifting & Duplication: After mastering the 72 transformations/Art of the Earthly Multitude (Chapter 2) Wukong gained the ability to change his form however he pleases. This can range from everything as tiny as a mustard seed (Chapter 65) to larger than a mountain. (Chapter 3) (Chapter 6) Wukong alleges he could be as big as the universe if he wanted to, though this is possibly hyperbole or a translation quirk. (Chapter 14)
This shapeshifting ability extends to each of the individual hairs on Wukong’s body. Using the hairs he can make duplicates of himself numbering in the thousands (Chapter 2) (Chapter 5), all of whom can also change their form just like Wukong. (Chapter 64)
And contrary to the name ‘72 transformations’, Wukong’s shapeshifting abilities extends to much more than 72. He can assume pretty much any shape he wants. (Chapter 90) Including…
A sparrow (Chapter 6)
A fish (Chapter 6)
A fake pill of immortality (Chapter 17)
A pangolin (Chapter 73)
A fly (Chapter 75)
Golden threads (Chapter 68)
Forks (Chapter 73)
Other people such as his master, Tansang Zang (Chapter 78)
A Buddhist Temple (Chapter 6)
A pointed knife (Chapter 14)
A tiger (Chapter 34)
Iron (Chapter 25)
And many, many more.
He can even mimic his opponents by assuming their form. Like when he mimicked the deity Prince Nezha’s transformation into a giant 3-headed, 6-armed monstrosity. (Chapter 3) Wukong also has some degree of intangibility since he can turn himself into vapor (some translations say ‘ether’). (Chapter 34)
These transformations can be performed on other people too. Wukong once disguised Pigsy and Sandy as clay statues (Chapter 45), and changed his master’s appearance into his own. (Chapter 78) To top it off, Wukong can alter and stretch his form (Chapter 97), or selectively change different parts of his body. (Chapter 25)
Theoretically, Wukong almost always has the option of having his duplicates fight for him while he hangs in the back. He has done this in some instances. (Chapter 73)
The only flaw in these transformations is they can sometimes have imperfections. (Chapter 6) (Chapter 34) Though being completely fair, these imperfections are rare, and in other instances Monkey has made disguises that are indistinguishable from the real thing. (Chapter 78)
Wind & Cloud Manipulation: Wukong has created hurricanes (Chapter 28), whirlwinds (Chapter 44), masses of clouds large enough to blot out the sun, and winds powerful enough to reach Buddha’s throne and ‘shake the foundations of the Five Phoenix tower’. (Chapter 3) Perhaps the most well-known demonstration of this power is Wukong riding a cloud, and moving said cloud with his wind magic. He can do this to get himself, and others around. (Chapter 3)
Superhuman Acrobatics: While commonly depicted riding a cloud, Wukong will often travel from one location to another just by leaping. He can travel hundreds of thousands of li in a single leap, (Chapter 2) or even to the edge of Heaven itself. (Chapter 7)
Light Walking: Besides clouds, it seems Wukong can walk on light as well. (Chapter 69)
Regeneration: Should Wukong get hurt, he’ll still be able to heal himself with an impressive healing factor. He has come back from decapitation, (Chapter 46) and getting his organs and entrails removed. (Chapter 46) A poem also strongly implies he can heal from other lost limbs. (Chapter 46)
One time, while disguised as his master, Wukong opened his chest and let out a giant pile of hearts. (Chapter 79) This was presumably done through a combination of his duplication powers and his ability to heal (also as a metaphor for the heart of a Buddhist I guess).
Superhuman Endurance: Wukong regularly fights long, extensive battles. He fought the Chinese god Erlang Shen to a stalemate for over 300 rounds straight, (Chapter 6) and has battled foes for half a day straight. (Chapter 95)
Barriers: Wukong can create invisible barriers stronger than an iron wall by drawing circles in the ground. (Chapter 50)
Fire Breathing: Wukong very briefly breathes fire in one of the later chapters. (Chapter 81) It’s never used offensively, but there’s no reason to think it couldn’t be.
Astral Form: Early on in Journey to the West, Sun Wukong’s soul was taken by several demons and brought to the World of Darkness. But unsurprisingly, this wasn’t an issue for Wukong, who simply beat up all the demons in the World of Darkness as a spirit. (Chapter 3) While he never fully dies after this point, presumably Wukong could keep fighting as a ghost if he did, or at the very least keep fighting if someone removed his soul from his body.
Demonic Detection: After being stuck in Laozi’s cauldron for 49 days, Wukong gained the ability to see demonic presences and see through their disguises. (Chapter 65) He’s also just naturally good at seeing through these disguises because many of the tricks demons will use he has done himself in the past. (Chapter 80) It’s possible this special detection is from the glow his eyes give off. (Chapter 95)
Enhanced Vision: Wukong can see great distances. Much further than an average person would be able to. (Chapter 22)
Terrain Shrinking & Alteration: Wukong can shrink and alter terrain to shorten distances. This magic is powerful enough to move even mountains. (Chapter 40)
Medical Expertise: Oddly enough, Wukong seems to have some knowledge of medicine and pharmaceutics. In one of the later chapters, he diagnoses a King with ‘melancholy’ and devises a cure for him. (Chapter 69)
Power Bestowment: Wukong can give other people his inhuman strength. Once while teaching 3 princes martial arts, he cast a spell that made them strong enough to lift his staff. (Chapter 88)
Poison Resistance: This one is probably not legitimate, but in one chapter of Journey to the West, Wukong was confronted with a foe who could control special sand stated to be poisonous enough to kill anything that got said sand in its nostrils. (Chapter 70) The sand did go into Wukong’s nostrils, but he just… Sneezed it out. (Chapter 70)
That said, Wukong was affected by a scorpion spirit’s poison in a prior chapter, (Chapter 55) and it’s implied he would have been vulnerable to the poison that was placed in his tea in a later chapter. (Chapter 73) So it’s likely something he at most only has minor resistance to.
Victorious Fighting Buddha: Upon completing his journey, Wukong ascended and achieved the status of Buddhahood. While we do not see him perform any feats upon achieving Buddhahood (because his story was basically over), he should presumably be comparable to the Buddha Siddhartha himself. Which is very impressive given said Buddha quite literally holds all of creation in his hand. That said, for the purpose of the fight, the focus will most likely be on Wukong’s pre-Buddhahood feats.
Strength & Destructive Power
-Created a mass of clouds large enough to blot out the sun, and winds powerful enough to reach Buddha’s throne and ‘shake the foundations of the Five Phoenix tower’. (Chapter 3)
-Regularly swings around a staff weighing 13,500 catties (around 17,500 lbs). (Chapter 3)
-Destroyed 5 Phases Mountain. (Chapter 14)
-Pushed down a large fruit tree. (Chapter 25)
-Made a hurricane. (Chapter 28)
-Held Mount Sumeru and Mount Emei on his shoulders. (Chapter 33)
-Lifted a cart full of bricks, tiles, and timber. (Chapter 44)
Speed & Agility
-Can travel 108,000 li in a single somersault. (Chapter 2)
-Leaped to Alolai in one jump. (Chapter 3)
-Outsped the Gold Star of Venus while flying to Heaven. (Chapter 3)
-Traveled from Flower Fruit Mountain to Heaven in a single somersault. (Chapter 5)
-Leapt to the edge of Heaven. (Chapter 7)
-Moved at the speed of a meteor while carrying two mountains (note: some translations say the speed of a shooting star, though that would just make him faster). (Chapter 33)
-Grew his staff quickly enough to breach through the 18 layers of Hell. (Chapter 3)
-Flew to the Southern Gate of Heaven in a short period of time. (Chapter 51)
-Flew to the Eastern Gate of Heaven in an instant. (Chapter 55)
Durability & Survivability
-Withstood being crushed under the Buddha’s hand and Five Phases Mountain. (Chapter 7)
-Withstood being at the epicenter of the Yellow Wind Demon King’s winds, which threatened to destroy the universe. (Chapter 21)
-Withstood being crushed under 3 mountains. (Chapter 33)
-Took direct blows from the bladed edged weapons of demons without a scratch. (Chapter 34)
Who does Sun Wukong scale to?
Sun Wukong should scale to the vast majority of the demons and gods in his world. He has either matched or defeated most of them, even the few he’s had trouble with he has fought in an extended battle. This includes Erlang, the Great Immortal, the Great Yellow Wind Demon King, Red Boy, The King of Miraculous Response, Princess Iron Fan, the Dragon King, the Bull Demon King, ETC.
The only exception would be the Buddha himself, who took down Wukong without any issue.
Great Yellow Wind Demon King
-Created winds that threatened to destroy the entire universe. (Chapter 21)
King of Miraculous Response
-Froze the heavenly river so it was traversable. (Chapter 46)
-Created winds spanning 250,000 miles of terrain. (Chapter 60)
Though very clever and notoriously difficult to kill, Monkey does have several shortcomings. His transformations sometimes have imperfections. Usually from his tail, which can be difficult to change. (Chapter 6) (Chapter 34)
Special fires such as the fire of Samadhi can also bypass his invulnerability. In the case of his fight with Red Boy, the temperature change Wukong experienced when he dove into a river after being set aflame by the fires of Samadhi was an intense enough shock to temporarily kill him, requiring him to be revived by Pigsy. (Chapter 41)(Chapter 41)
Wukong has also been hindered in the past while fighting in water. This is because he has to either transform into a fish or water animal, or make hand signs to move water around. He can't fight using his staff while doing either. (Chapter 49) While it never comes up in his journey, this specific weakness does imply he may need to focus to cast certain spells, and may not be able to both fight and cast spells simultaneously.
Lastly, Wukong has been affected by deadly poisons. Most notably, the horse-killer poison used by the scorpion spirit. This was bad enough that he had to retreat from his fight and be healed by the Star Lord. (Chapter 55) Being fair, this poison should be very powerful, it affected even the Buddha of all people. But it does show that while Wukong is immortal, he isn’t unkillable.