The Four Star Dragon

The sun seems unusually hot, and they discover that it is because of the four-star dragon. He can raise his body temperature to even greater levels than the surface of the sun, which makes punching him out of the question. Goku is forced to run from the dragon. He realizes that he can still use energy waves, so he begins attacking the dragon. After a while, the dragon gets tired of playing around, and he changes into his final form. Goku follows suit, and transforms into a Super Saiyan 4.