Event 40: The Final Battle
From SmashWiki, the Super Smash Bros. wiki
The Final Battle (最終決戦, Final Battle) is the 40th and penultimate solo event match out of a total of 41 in Super Smash Bros. Brawl. This event pits the player against the Nintendo game antagonists, Bowser, King Dedede, and Ganondorf, while on Final Destination. The player has two stocks while each opponent has one stock. Despite the name of this solo event, this solo event may seem like the final one in the game. But if one completes all other 40 solo events, the player unlocks the secret 41st solo event (which has even harder enemies).