Big Bully. He is also faster, harder to push, pushes harder, and Luigi must push him off the stage three times. When you push him of the stage he will return to the middle trickier and stronger each time, but after the second time he will jump back to the middle if you try to push him near the edge of the stage, so you have to either hit him from the side, while he is not looking, or when he is charging. After he is pushed off the third and final time you win.
Chief Chilly, like all other bosses he comes from Super Mario 64 DS in the mission "Chief Chilly Challange".