Marx would later make an appearance as a Dream Friend in Kirby Star Allies in order to help Kirby, implying that the both of them are now at least on neutral terms with each other.
In his first form, Marx appears to be a small jester with no legs, arms or hands. He wears brown shoes with small light brown dashes going across them that look like shoelaces. His skin is lavender with two big expressive purple eyes that lie under his hat. His hat is divided into two colors with different shapes on each side: red with white triangles on the left side and blue with white circles on the right. Marx wears a red bow tie under his mouth, which has a fixed smile and two small fangs that are only visible when his mouth widens. His beach ball is striped with the colors of his hat: red, white, and blue, although artwork shows a yellow stripe on it.
After Marx makes his wish to take control of Popstar, he transforms himself into a fearsome bat-like monstrosity with golden yellow-colored wings with two sharp fang-like claws jutting out from each one. The wings also have flashing mirror-like, multicolored, hexagon-shaped scales under them. Each wing has a red heart on it. His skin retains a purple hue (though his skin adopts a darker shade of purple in Kirby Super Star Ultra), but his eyes are big and black. Marx has a bigger mouth and Marx's bow tie is noticeably larger, but it appears to be coming undone. Lastly, his shoe color remains the same, but the shoes themselves are longer and are rounded at the ends. His eyes' pupils are also apart from each other as opposed to being placed central (being somewhat inverse-cross-eyed) which shows signs of slipping sanity, unless he performs certain actions (such as certain attacks).
In the manga, Marx looks very similar to his first form, except he now has arms with gloved hands and eyebrows, unlike any of his video game appearances.
While Marx appears to initially be friendly at first, he reveals himself to actually be cunning and manipulative, as he tricked Kirby into doing the dirty work for him in Milky Way Wishes. He also appears to be a bit of a prankster, as shown in Kirby Super Star Ultra where he says “Now I can cause all the mischief I want!”, and also in two pieces of artwork from the official Twitter account. In Kirby Star Allies, it is stated that Marx will be buddies if he is kept well-fed, implying that he is rather ravenous for food and will befriend those who give him such.
Marx makes his first appearance in the Milky Way Wishes sub-game in Kirby Super Star. When the sun and moon of Planet Popstar start fighting each other and knocking each other out of the skies, a small jester-like being who goes by the name of Marx tells Kirby that the only way to stop the fight between the two is to gather the power of the surrounding stars and use them to summon Nova, a planet-sized, mechanical "comet" that can grant wishes. Before Kirby hops on the Warp Star, Marx wishes him good luck.
After gathering the power from the seven planets' Fountains and summoning Nova, Kirby goes on to make his wish to save Popstar. Just then, however, Marx knocks Kirby off-screen and makes his own selfish wish — to take complete control of Popstar. When this happens, he transforms into his monster form and gains new superpowers. It turns out that he actually tricked the Sun and Moon into fighting each other, tricked Kirby into doing his dirty work for him, and revealed that this was all part of a master plan to conquer Popstar. Afterward, Nova begins looming towards Popstar, leaving Kirby alone in space. The power Kirby had gathered comes together, however, and creates a Starship for him to stop Nova with. Nova's journey to Popstar is suddenly hampered by the sun and moon, giving Kirby the chance to enter him. When Kirby destroys his heart, Nova is injured, making Marx extremely irate, so he then attempts to attack Kirby himself. In spite of Marx's fearsome and deadly new superpowers, Kirby manages to win, and send Marx flying away and into Nova's broken head, seemingly destroying them both in a massive explosion.
Marx's role in the Nintendo DS remake, Kirby Super Star Ultra, is essentially the same as the original game, but there is a slight twist concerning his fate. A clip shown towards the end of The True Arena reveals that he was destroyed after the events of Milky Way Wishes, but his body had begun to absorb dark energy and Nova's power, not only reviving him but also transforming him into the even stronger Marx Soul, granting him even more power than ever before. After a series of battles against Kirby's toughest enemies, Marx Soul appears in a colorful but dark and distorted dimension as the final foe. Denied his revenge and overthrown once more, Marx Soul lets out a bloodcurdling scream as he slowly splits in half, turning a deep shade of purple, and blowing up the whole arena in the process.
Marx appears in the Special-Edition Blooper Reel movie in Kirby Super Star Ultra. He is seen in the second-to-last last clip. When he tries to tell Kirby and friends how to stop the Sun and Moon from fighting, he slips and falls off his ball and on the ground before he even gets a chance to talk. Marx even appears in the Kirby Master cutscene when Kirby completes a file with 100%, having a front row seat in the audience for Kirby's performance. Strangely, despite his harsh feelings towards him seen in the past sub-games, and the fact that he was defeated three times by him in this version (once in Milky Way Wishes, again in The Arena, and for the last time in The True Arena), he cheers for Kirby after he does his Victory Dance.
Marx makes an appearance as the final boss of the Kirby Brawlball sub-game on a board resembling that of the battlefield's landscape. He is much bigger than he originally appeared, and he uses revamped versions of his original attacks. Illusions of his normal form also occasionally litter the ground, walking on their beach balls. If the player manages to get Kirby to bounce on their heads, the player acquires two additional Kirbys.
Marx appears as a Dream Friend for the first update to Kirby Star Allies, primarily using his jester form. Apparently, Marx somehow survived the crash into Nova in Milky Way Wishes and sensed danger from afar, coming to Kirby's aid, despite their past history, in order to stop the threat looming over the galaxy. Marx uses most of his attacks from his boss fight in Kirby Super Star and Kirby Super Star Ultra. He also uses his ball to roll around and attack. His attacks can be enhanced with any element, which changes how some of his moves work.
In the 2.0.0 update, a statue of Marx performing his Black Hole move may be seen when Kirby uses the Stone ability.
In the 4.0.0 update, Marx was added as a bonus boss. When playing the Credits Game after clearing the Heroes in Another Dimension sub-game, Marx appears to challenge Kirby like King Dedede or Meta Knight would in different modes. The player has a limited time to defeat him before he flees the stage. He uses all of his attacks from Kirby Super Star and Kirby Super Star Ultra, while using the laughter from the latter game. Should Marx's attacks hit the player or any CPUs present, 500 points are taken away.
Marx charges forwards surrounded by a rainbow aura. This can be chained in succession with other presses of B, transition into a Marx Megaspin with ↑ + ↓ + B, or transition to a Marx Flip Ultima with ↓ + B.
Radiant Flight + L/R
Marx teleports a short distance forward. The teleport direction can be angled. This move can be repeated by tapping L/R after teleporting.
Blizzard Marx's ball creates a temporary, damaging mass of ice on the floor, wall, or ceiling on which it bounces.
Bluster Marx's ball descends more slowly, giving it more air time.
Sizzle Marx's ball leaves a small blaze.
Splash Marx's ball leaves a small watery burst.
Zap Marx's ball leaves a small spark.
Jester Ball Ride
Allows Marx to roll across lava.
If Marx jumps, the ball will lift him up into the air and he will be able to float in any direction.
Allows Marx to roll across lava.
Leaves a spark trail on water.
Explosion of a ball
A larger batch of crystals is formed.
Creates a large whirlwind.
A larger blaze is formed.
A large burst of water is formed and two droplets arc out.
One vertical lightning bolt is summoned.
The enemy or object thrown has the properties of an ice projectile.
The enemy or object thrown has the properties of a wind projectile.
The enemy or object thrown has the properties of a fire projectile.
The enemy or object thrown has the properties of a water projectile.
The enemy or object thrown has the properties of an electric projectile.
Wings resemble ice crystals.
Wings are pale green.
Wings are red and burning.
Wings are blue.
Wings have a green hue and are electrified.
Jester Ball Spit-Drop
Two large circular projectiles shoot out to either direction from the site of impact and freeze enemies, similar to those from his Kirby Super Star boss fight.
Summons four cutters of wind like in the Kirby Super Star boss fight; thee cutters can cut through ropes and [fire] chains. The ball creates a large whirlwind on impact.
Summons two arcing fireballs at the explosion.
A thorny cactus like that of the Kirby Super Star boss fight grows from the site of impact.
Shoots two diagonal lightning bolts from the explosion.
24 (Ice Bomb Wave) 14 (Shooter Cutter)
Marx Megaspin, Rush
Icicles are formed along the flight path. The icicles fall to the ground, damaging enemies and creating crystals.
A huge cyclone appears at the end of the Megaspin. Creates gusts behind Rush, traveling a wavy path.
Shoots fireballs ahead of Marx.
Water drops are ejected during flight.
Shoots electrified arrows resembling those of the Kirby Super Star boss fight.
12 (Thunder Arrow)
Marx Flip Ultima
Four huge ice stalagmites are formed on the ground.
Multiple large gusts are left behind as Marx ascends from the ground, which let Marx travel higher.
Four fireballs burst out of the ground with Marx.
Six water drops burst out of the ground.
Four lightning bolts burst out, two of which run parallel to the ground.
Marx's attacks are generally predictable but very powerful. Marx has five attacks that follow a simple, but very distinct pattern. He starts out by shooting out four crescent blades at Kirby as soon as he appears. He then flies up, going off the screen, and drops four small seeds that grow into four large, thorny vines that appear in the same spots the seeds fell in. After the vines grow and disappear, an electrified shadow appears and begins to follow Kirby around the floor. After a few seconds, Marx springs up from the ground and flies into the air, but comes back down. Marx teleports off-screen and reappears at the side of the screen, glowing blue at this time, and shoots out a stream of arrows at Kirby. Marx flies off and then reappears above Kirby and soon his cheeks puff out. Marx soon spits out a black ball at the ground, which turns into two ice balls that slide across the screen according to Kirby's height level. Finally, Marx's cheeks puff out again while he's glowing, and spits out a giant white beam. Marx soon teleports himself all over the place multiple times in a row. This pattern starts again, but after taking enough damage, his attack patterns will become more random and unpredictable. His newest attack is that he can split himself in two symmetrical halves and reveal his iconic attack - the black hole. Kirby will take extremely heavy damage if he gets sucked into it. Fortunately, this is his slowest and most predictable attack, although it should be kept in mind that the black hole has a considerable range and guarding is ineffective against it. An interesting fact about the battle is that, in the remake, after Marx has taken sufficient damage, the screen will occasionally start changing between blue, green, and red, possibly an effect of him straining his powers to the maximum in an effort to finish Kirby off for good.
Marx appears as a boss in Super Smash Bros. Ultimate. He appears in Classic Mode as the boss of Kirby, Inkling, and Rosalina & Luma's routes, as well as in World of Light, where he is fought in the Mysterious Dimension of the Dark Realm. He uses almost all of his attacks from his boss fight in Kirby Super Star and Kirby Super Star Ultra apart from his arrow barrage attack. The seeds he drops on the ground now sprout dark branches of energy rather than green vines. He also has some new attacks as well. He can turn his eyes pitch-black in order to make them fall out of their sockets and bounce toward the player, dealing darkness damage after hit. He can enlarge his eyes, to the point where they protrude out of their sockets, grow many pupils on them, and shoot four lasers (five in Hard mode) out of each eye. His eyes slightly rotate, causing the lasers to rotate as well. Lastly, he can retract his wings in order to spread veins throughout the areas to his sides, burning the player on contact. After defeat, he screams and his body violently bounces across the arena, his wings break off, and he reverts back to his original form and lies lifeless on the ground, burning in purple flames for a second.
When defeated in World of Light, the player receives his spirit (in jester form). It is a Primary, Advanced-class, Grab spirit that can be enhanced into Marx’s winged form, which is a Primary, Legend-class Grab spirit. While his Advanced-class spirit sports no effect, his Legend-class spirit increases Magic Attacks.
Marx's hat also appears as wearable headgear for the Mii Fighters.
Marx is a character in Kirby Super Star and Kirby Super Star Ultra. He was a diminuitive jester of Dream Land with big plans. He made the Sun and Moon of Dream Land to fight with each other, and asked Kirby to summon Nova using the powers of the Dream Fountains of surrounding planets and wish the fighting to stop, but he has his own plans for that one wish Nova can grant - complete control over Dream Land.
Hey, hey, hey. Can you make peace between the Sun and Moon? You need to ask the giant comet Nova for help! But first, there's something we must do. To ask Nova, we must gather power from all the stars around us. It will be difficult, Kirby, but you can do it! We are counting on you. Good luck!”
WOW! It worked. The Sun & Moon are fighting. Go find Nova. All my plans worked! Popstar is all MINE! Now, I can do anything! I must be going now. Hahahahahahahah....”
— Marx to Kirby • Kirby Super Star
I did it! It all went according to plan! I got the sun and moon to fight. I got you to go into space... it was all according to my perfect little plan! Now I can cause all the mischief I want! Haha! See you later!”
— Marx to Kirby • Kirby Super Star Ultra
Marx has shown his true form! Fly in and protect Pop Star! Do it, Kirby, our Super Star!”
The famous jester from Kirby Super Star has finally arrived to get in on the action! Sure, he's had a diabolical past as a final boss, but he'll be your buddy if you keep him well-fed. It's a dream come true!”
— Flavor Text • Kirby Star Allies
A magic hat lovingly dedicated to the ultimate jester. It was inspired by the clown who wished on a star to make it his own.”
Despite Marx's Japanese name translating closer to "Mark", the Japanese version of The Arena and Kirby Mass Attack renders it Marx.
Artwork of Marx in the Japanese manual for Kirby Super Star seems to suggest that Marx is wearing glasses. This detail is left out in other artworks of Marx.
Marx wears a hat near identical to the original hat worn by Mirror Kirby, which also debuted in Kirby Super Star. The two colors on the hat are reversed on Marx's hat and the blue part on Mirror Kirby's hat is more of a teal color. This coincides with the colorful mirror-like panels that stream down Marx's wings, or him splitting in half like Mirror Kirby to perform the Black Hole move.
Marx's laugh was changed in the remake; it was a warped sound effect in the original, but he was given a demented high-pitched laughter in the remake. In Kirby Mass Attack, his laugh is similar to that in the remake, but the actual board design is closer to the original version.
A portrait of Marx alongside some other final bosses is shown in Kirby: Squeak Squad in one of the collectible pieces of artwork obtainable from Treasure Chests.
A split second before Marx is powered up by Nova, he looks similar to Marx Soul. This is true even in the original SNES game.
Additionally, both were villains who deceived Kirby, and their use of elemental attacks is similar. The black hole attacks used by both villains have the same visual effect: if Kirby is sucked in, he is transported briefly to an alternate dimension where he takes severe damage. Both Marx and Magolor shoot out giant beams that cause heavy damage, and they both teleport themselves to different places around their respective arenas, and launch projectiles at Kirby.
Marx and Magolor also appear together in a stone transformation first appearing in Kirby: Triple Deluxe, as well as in a skit on the title screen of Kirby Star Allies, which could further imply a connection between the two. Although, it could also just be referencing that they were the only two villains who had backstabbed Kirby instead.
Strangely, the surface of the arena that Kirby fights Marx and Marx Soul on appears to scroll rapidly from the right, even though Kirby may appear to be standing completely still. The same effect was seen in Nightmare's battle in Kirby's Adventure and Kirby: Nightmare in Dream Land.
Two balloons appear in the background of the highest level of Kirby Star Allies‘s Goal Game. One is blue with white dot patterns and the other is red with white triangle patterns; they are held together with a red bow tie. These appear to be a reference to Marx.
When Marx's ball is enhanced with an element in Kirby Star Allies, the hexagon pattern on his wings will change to a single color.
Interestingly, in Kirby Star Allies, the Marx featured during the credits of Heroes in Another Dimension also includes in-game data that includes his theme song and a health bar, despite the fact these two features are not actually utilized or displayed in the end credits fight.
Kirby Star Allies Marx, the Cosmic Jester - Nintendo Switch