Paper Mario how do you beat o'chunks?

Answer 1

You use Thoreau to pick him up. Then throw him, and after that jump on his head while he's dazed. Repeat.

Answer 2

Use the Pixl Thoreau to grab him and throw him. Immediately, while he is dazed, jump on his head. Repeat this until he loses.

Answer 3

Jump on him. You can use Thoreau to KO him. While he is KO'ed, it may be easier to attack him.