Waluigi

Waluigi is a character from the Mario franchise, in which a majority of his appearances are in the spinoff titles, usually as a playable character. Waluigi is Wario's partner and Luigi's rival. In the Super Smash Bros. series, Waluigi first appeared in Super Smash Bros. Melee, as a collectible trophy, and has been an Assist Trophy in every title since Super Smash Bros. Brawl. Since his overall debut in the Nintendo 64 game Mario Tennis, Waluigi has been portrayed by Charles Martinet.

Waluigi is among one of the more requested fighters for the Super Smash Bros. series, but is yet to make a playable appearance.

Super Smash Bros. Melee
In Super Smash Bros. Melee Waluigi is featured as an obtainable trophy, and can be acquired via the Lottery after collecting at least 250 other trophies. His description states that he spends a large quantity of time training for Mario Tennis, "honing" the ability to annoy Mario and Luigi. The description also notes that he is the same age as Luigi, and that the status of his relationship with Wario is unknown.

Super Smash Bros. Brawl
In Super Smash Bros. Brawl, as an Assist Trophy character, Waluigi appears with a tennis racket in hand, referencing the Mario Tennis series. He kicks his chosen opponent into the ground and finishes up by delivering one final kick or a blow with his tennis racket.

The game also features another trophy of Waluigi, as well as two stickers depicting his appearance in Mario Superstar Baseball and Super Mario Strikers respectively. Both stickers can be used by Bowser, Peach, Yoshi, Mario, and Luigi, and both increase attack; the former increases the user's long-ranged special attack by eight, and the latter increases the user's strength of moves which use claws or blades by fifteen. His trophy appearance, with includes his tennis racket, again has a description which notes that his relationship with Wario is unknown, and that he worked "silently in the shadow of the Mario Bros." before he could compete against them in Mario Tennis.

One of Luigi's alternate costumes resembles Waluigi's outfit.

Super Smash Bros. for Nintendo 3DS / Wii U
Waluigi appears as an Assist Trophy again in Super Smash Bros. for Nintendo 3DS / Wii U. Additionally, Luigi regains his Waluigi-inspired alternate costume (albeit with a purple L instead of yellow) while Mario gains a similar alternate costume, the only difference being that his M is yellow like Waluigi's Γ.

Super Smash Bros. Ultimate
Waluigi returns in Super Smash Bros. Ultimate as an Assist Trophy. Two spirits of Waluigi appear, one of which uses artwork of his regular appearance, the other using his artwork from Mario Strikers Charged. He also appears in the Standard Bike's spirit. His regular appearance fight has Waluigi appearing as an Assist Trophy enemy, and takes place on Peach's Castle. His Spirit fight for his Mario Strikes Charged appearance has the Soccer Ball item rule and takes place on Wuhu Island. Both fights are against Luigi, referencing his rivalry with him. Mario and Luigi retain their Waluigi-inspired alternate costumes.