Character description
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. Along with this, Waluigi has a hat and gloves with an "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 (though the game "Mario & Sonic at the Olympic Winter Games" on the Nintendo DS disproves this, saying that Waluigi is actually Wario's co-partner, despite the fact that he has never appeared in a WarioWare game) 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.
Waluigi appears as a trophy in Melee, that can be unlocked by either playing Classic Mode or the Lottery.
 Trophy Description
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.
 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.
 Assist Trophy Origin
Waluigi made his first appearance in Mario Tennis and has appeared in nearly every Mario spin-off since. In Brawl, Waluigi appears as an Assist Trophy holding his tennis racket, which is a reference to his first appearance in Mario Tennis. He will try kick players into the ground; however, Waluigi has never done this in any other game. His finishing move either involves kicking the player, or hitting the player with his tennis racket. His appearance has slightly changed in Brawl, Waluigi has orange shoes in the Mario games, not brown. Although the tennis racket he is holding has retained its design from Mario Tennis.
 As a trophy
Waluigi also appears as a randomly collectible trophy:
 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.
 As stickers
Waluigi also appears as two stickers, both of which are exclusive to Mario, Luigi, Peach, Yoshi, and Bowser. One uses his artwork from Mario Superstar Baseball, and the other one uses his artwork from Super Mario Strikers.