Event 1: Trouble King
From SmashWiki, the Super Smash Bros. wiki
Trouble King (迷惑大王, Annoying King) is the 1st event match of the 51 event matches in Super Smash Bros. Melee. As Mario, the player must win a 2 stock match against a CPU Bowser on Battlefield with no time limit. When the match starts, the player spawns at center of the main platform, and Bowser spawns above the topmost platform. Bowser is heavily handicapped and his AI is only level one.
The track that plays in this match, Multi-Man Melee 2, is not used in any other event match until Event 51: The Showdown. In this regard, the two event matches can serve as bookends in the game (marking both the first event and the fifty first and final one).