Mario Tennis is a 2000 sports video game developed by Camelot Software Planning and published by Nintendo for the Nintendo 64. Following Mario's Tennis, it is the second game in the Mario Tennis series. The game is known for being the introduction of Luigi's arch-rival, Waluigi, and the re-introduction of Princess Daisy and Birdo.

Waluigi is a character in the Mario franchise. He plays the role of Luigi's arch-rival and accompanies Wario in spin-offs from the main Mario series, often for the sake of causing mischief. He was created by Camelot employee Fumihide Aoki and was voiced from 2000 to 2022 by Charles Martinet, who described Waluigi as someone with a lot of self-pity. Waluigi's design is characterised by his tall stature, thin and lanky frame, and his purple and black outfit with purple hat, which displays an inverted yellow "L".