Bowser vs. the entire Brawl roster - Brawl Co-op Event 21: The True All-Star Battle (Solo)

This wasn't really difficult with Bowser. Fortress is tremendously useful here, and a bunch of Bowser attacks have high base knockback that allows to him KO very early, including a dash attack that OHKOs here with its tremendous base knockback. Additionally, Bowser's attacks are pretty easy to land here on the AI, and he can take a hell of a beating before dying. Bowser's item play is subpar, but it's an inconvenience here at most.