Event 45: Game & Watch Forever!
From SmashWiki, the Super Smash Bros. wiki
This event match requires KOing 25 light Mr. Game & Watches to complete the event, in similar fashion to the final stage of All Star (where the player fights Mr. Game & Watch; 25 of them). The player has three stocks, while the other 25 have only one each. However, the player's Mr. Game & Watch is also light.