Waluigi's first appearance was in what game?

The story behind the answer

Mario Tennis 64 (N64) is correct because Waluigi was created by Camelot specifically for that 2000 game to serve as Wario’s doubles partner and Luigi’s rival. He did not appear in earlier titles like Wario Land: Super Mario Land 3 (1994) or the first Mario Party (N64), and he wouldn’t show up in Super Smash Bros.