First you can break down the walls in the final floor and get some purple pikmin. After you do that go to the arena and he will come down. Throw purple pikmin on his back and he will turn purple. Keep doing this until he is not on his rollers. Then he will run around like a chiken but don't worry he will stop and it will be your chance to kall him then head for the guyser after you get his treasure.
Sorry it took to long my computer was just broken.