When Pyukumuku is summoned, it will do nothing unless a fighter tries to interact with it. If attacked or touched by any fighter, it'll perform a wide and strong swing with its fist-like organs that covers a large area. This attack knocks back opponents a fair distance. If attacked from behind, Pyukumuku will not turn around to hit its attacker. Whomever summoned Pyukumuku can also pick it up and throw it like they would a regular item, also causing it to perform its swiping attack. This can make it very useful as an edgeguarding tool that you can throw at recovering enemies. If it falls beyond the screen's boundaries, it will not respawn, so make sure not to miss if you decide to throw it offstage: you only get one shot. When its time is up, it will wave "goodbye" with its "hand" before leaving.
Pyukumuku also appears as a Novice-class Support Spirit, available to purchase from the shop or as a random encounter from the Spirit Board. Its spirit battle is a team battle against a team of 4 Kirby puppet fighters at the Frisbee Dog Park portion of Wuhu Island. The stage references Pyukumuku being often washed up on the beaches of Alola, and are tossed back in by locals to prevent them from drying out.