Ategev is Vegeta's sick and twisted clone. Five years after Vegeta's death, scientist's tried cloning him since nobody knew where Goku was at the time and they wanted a hero to watch over them. Unfortunately, the only scientific lead they had on cloning was a cheap Star Wars movie rented from blockbuster, So they tried to reanimate him in a duplicated cloning tank (which George Lucas sued them for later) and things went terribly wrong. He killed the scientists (who were thankful that their lawsuit was dropped) and went to find Goku. Eventually he got tired of searching and just started blowing things up. Goku heard the sound of melting city (LOL, llamas with hats 4) and came to the rescue. He and Goku fought for a long time, Goku even landed a hit on him with X10 Kamehameha. Ategev was too strong for Goku, even in his super saiyan 5 form, so he did the only thing he could do, the Spirit Bomb. Apparently Goku was so used to making Spirit Bombs He just materialized one in one second (DAMN that was fast!) but having all Vegeta's memories and stuff Agetev saw it coming and deflected the attack. Then Goku made a more powerful one and blew him up.