Waluigi has so far only appeared in spin-off and party games, as opposed to the main platformer titles, save for a few negligible cameos. He is Luigi's evil rival, in the same way that Wario is Mario's evil rival. Along with this, Waluigi has a hat and gloves with a "Γ" gamma symbol, which is similar to Wario's "W", which is also an inverse or an upside-down "M". Unlike Luigi's green hat and shirt, Waluigi has a purple shirt and hat with black overalls, while his Γ symbol is yellow. He is believed to be Wario's younger brother (although this is unconfirmed) as well as one of his many friends. Waluigi was created by Camelot's Fumihide Aoki and is voiced by Charles Martinet, like Wario and both Mario Bros. His favorite weapon is a Bob-omb.
Waluigi appears as a trophy in SSBM.
This tall, thin, evil-looking guy seems to be Luigi's rival. He works hard at his mischief: Waluigi reportedly spent a lot of time training for his debut in Mario Tennis by honing his ability to antagonize the Mario brothers. While it's general knowledge that he's the same age as Luigi, his relationship to Wario is unclear.
- Game: Mario Tennis (08/00)
As an Assist Trophy
Waluigi appears as an Assist Trophy in Super Smash Bros. Brawl. He has brown shoes instead of his usual orange shoes. When summoned, he dashes at a random opponent on stage and stomps them into the ground (although he can stomp multiple opponents at once if others around are caught in the stomps), in a manner similar to Donkey Kong's Headbutt or the Pitfall. He stomps the victim(s) multiple times before unleashing a finishing blow with his tennis racket or a kick. His kicks spike if the opponent is a little outside the stage. Unless he attacks constantly, his final attack has a pause which lasts about 3 seconds. Also, he is relatively easy to avoid on the stage, but chances are he is going to attack someone once.
As a trophy
Waluigi also appears as a randomly collectible trophy:
- A twig-thin man who sees himself as Luigi's ultimate rival. He spent a long time working silently in the shadow of the Mario Bros. before finally becoming strong enough to compete with them in Mario Tennis. Since then, he's had many brilliant game appearances. While the nature of his relationship to Wario is a mystery, the pair have hatched some devious schemes together.
- Mario Tennis (2000)
- Mario Kart: Double Dash!! (2003)
- Mario Golf: Toadstool Tour (2003)
As a color change
Luigi possesses a black and purple color swap which gives him a similar appearance to Waluigi. The L on his hat also changes to yellow, just like Waluigi's inverted L. The L, however, doesn't flip itself like Waluigi's does.
Waluigi also appears as two stickers. One uses his artwork from Mario Superstar Baseball, and the other one uses his artwork from Super Mario Strikers.
Via the hacking program BrawlBox, hackers have succeeding in replacing the model for the Red Alloy with Waluigi's model. Additional hacks have smoothed out Waluigi's motions and given him some original animations. However, like the Alloy he is replacing, he cannot use special moves or grab ledges.