Buu Saga

Seven years later Goku returned from the dead for one day with the help of Baba the Witch to compete in the 25th Tenkaichi Budokai.

A being considered to be an supreme god named, Kaioshin warned Goku about the sorcerer, Babidi and his plans to resurrect the ultimate evil Majin Buu.

Vegeta had plans of his own. He wanted to challenge Goku again since this would be his only chance.

Babidi had the Z fighters fight multiple opponents in order to gather energy for Majin Buu's revival. Dabura, one of Babidi's strongest fighters, discovered that Vegeta's heart wasn't as pure as the others and Babidi attempted to gain control of Vegeta to fight the other Saiyajins. 

Majin Vegeta

Vegeta then became Majin Vegeta and killed 100's of people in the martial arts stadium to get Goku to fight him. It was later revealed that Vegeta used this as an excuse just to fight Goku. Vegeta's pride proved too resilient against Babidi's mind control. Both Majin Vegeta and Goku were able to fight as Super Saiyajin 2 and were too evenly matched. Majin Buu was resurrected from all the battle energy. Vegeta and Goku agreed to stop to fight Buu.

Vegeta asked Goku for a Senzu Bean and knocked Goku out with a blow to the head. Vegeta was determined to fight Majin Buu alone. He was angry at himself because he couldn't feel Gohan's energy and blamed himself for allowing the energy for Majin Buu's revival.

Vegeta squared off against Buu (Fat Buu). Vegeta seemed to have the upper hand and even blew a hole right through Buu. But Majin Buu was able to regenerate.

Vegeta only saw one option. He gathered up all his energy and blew himself and Majin Buu up. But although completely in pieces Majin Buu regenerated.

Vegeta was then brought back to life to fight Super Buu. At this point Buu absorbed Piccolo, Gotenks, and Gohan. Buu proved to be too much of a match for Goku and Vegeta. They used the Potara earrings to fuse into Vegito. Majin Buu was no match for Vegito and tried to absorb him.

Vegito allowed this so he could get inside of Buu and free all the people he absorbed. Althought the fusion of Vegito was supposed to be permanent Majin Buu's body caused the two to separate. Goku and Vegeta saved all the people inside Buu and Vegeta ripped Fat Buu out. This caused Super Buu to become his most evil form, Kid Buu. Kid Buu responded by destroying earth.

Goku and Vegeta escaped to Kaioshin's planet. Majin Buu then sought out Goku and Vegeta and destroyed each planet he teleported too. Goku and Vegeta raised there power so Buu could find them. Goku and Vegeta fought Buu but Buu proved too tough.

Vegeta then distracted Buu giving Goku enough time to form a large Genkidama (Spirit Bomb) that finally obliterated Buu. Vegeta finally admitted at this point that Goku is number one, due to him always pushing himself past his limits.