Waluigi's only appearances have been in the Mario Sports/Party spinoffs. His only appearance in any game of consequence is as an Assist Trophy in Brawl, and his lack of previous experience probably explains why he attacks with a tennis racket when appearing in that capacity (a nod to his debut game). Dude really doesn't have much characterization of his own, and he probably gets most of his popularity from that webcomic.
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(this space for rent...okay, not really.)
[NO BARKLEY NO PEACE]