In Super Smash Bros. Brawl’s Subspace Emissary, Mario (often alongside Pit, Link, Kirby, etc.) confronts Petey Piranha as the boss of The Forest / Forgotten Land stage. It’s a scripted boss encounter, not a standard Smash match.
It’s a platformer-style boss fight woven into Smash’s engine — memorable for the cage-rescue mechanic and Petey’s scale.