From the Super Mario Wiki
Chomper Stomper is a quest in Mario Party Advance that starts when Chain Chomp is visited. When it is visited, it excitedly asks the player if they want to duel it: declining leaves it disappointed, and accepting makes it excited and starts the quest. It explains that if the player beats it at the Duel minigame, Chain Saw, they are allowed to keep it for themselves. Once Chain Chomp is defeated, it relents and rewards the player with the minigame.
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