Bowser Toy Shop
From the Super Mario Wiki
When the player decides to stop here, they will meet Bowser and his cohort, Koopa Kid. Their quest, Bowser's Toys, involves Bowser asking the player five questions about Toad Force V, and each one must be answered correctly. After that, he'll challenge them to the Duel minigame, Slammer. Defeating Bowser will earn the player the right to keep the mini-game.