Lemmy makes his Paper Mario series debut in Paper Mario: Color Splash. He appears in the Emerald Circus, where he is seen balancing on a giant ball. He then
hides himself and the green Big Paint Star on the circus tent's roof (as, despite being a skilled illusionist, the Green Big Paint Star was immune to his wand and his magical abilities, thus forcing him to pull a "sleight of hand."). After Mario defeats his minions, they encounter him on the roof, where the battle is fought.
In battle, Lemmy spawns Ptooies, Juggler Bros, and Circus Bros, to aid him by using his wand. He also uses his wand to make Mario's cards disappear. He attacks by ramming Mario with his ball, although he can also use this as a feint for a magical blast attack from his wand. Hammer attacks are ineffective against him. Finally, he is capable of dodging attacks from Thing Cards. Instead, it requires that Mario distracts him with the Disco Ball Thing Card, and then using an Ice Pick Thing Card to pop his ball, making Lemmy the only boss in the game that requires two Thing cards. If just the Ice Pick is used, Lemmy avoids the attack. If just the Disco Ball is used, Lemmy initially gets distracted, then resumes attacking after Mario finishes attacking. If Mario does not defeat Lemmy while he has his Wonder Ball out, Lemmy will use the Wonder Ballistic attack. Lemmy hits Mario 15 times, each dealing 10 damage each and then jumps on him dealing 13 damage, for a total of 163.
Lemmy is one of the three Koopalings that does not have an attack that can defeat Mario instantly when Mario has full health, even if Mario does not block them at all, the others being Morton Koopa Jr. and Roy Koopa. He is also one of the two bosses in this game that cannot be defeated with Thing Cards alone, the other being Ludwig von Koopa. The player must use regular battle cards to damage him in the first phase of the fight.
Lemmy's introductory pose is based on his artwork used in the Encyclopedia Super Mario Bros. and in material released for the 30th anniversary of Super Mario Bros., while his appearance follows that of the current games, with an additional cyan-colored tuft on the back and orange stripes on the left side of the head instead of the right side. The sprite was actually a horizontally flipped version of said pose that is then flipped again by the game. Lemmy's pose when he extracts his Magic wand is instead derived from his artwork in Super Mario Bros. 3, with the mouth now being slightly open, the right hand now holding the wand more tightly and left hand showing the palm to the viewer.