" @TheManipulater: He won't. This isn't really the overpowered Goku of the DBZ. Up to that point he was about a mountain-buster. Their powers are almost equal with a slight bias to Goku. Kenpachi could slice building complexes with a lazy swing and the shokweaves of his and Ichigo's final clash destroyed a whole discrit at Soul Society. Also in the movie he lifted a column with the size of a large hill with pure Reiatsu pressure. Certainly, you seriously underestimate Kenny and forget that Goku wasn't a godlike fighter at the start of DBZ. "Sorry but Pre-Kaioken Goku is Moon Buster Level.
Raditz Saga Piccolo blew up the Moon with little effort, Roshi Blew up the moon previously in tournament as well.
Also other people have already posted Goku durability and strength at that time.