Piccolo was Goku's enemy until DBZ where they team up to fight and defeat Radditz. Piccolo then takes Gohan under his wing to train him. Gohan becomes a strong warrior because of this. Piccolo is killed by Nappa, and later brought back to life on Namek where he fights Frieza and loses. Piccolo is sent back to earth and comes back later when Buu arrives. After Goku goes back to the other dimension he takes over training Goten and Trunks to fuse.
