Summary of Majin Buu

When he emerges from his egg for his first apperance, Majin Buu is pink, fat, and round, and his personality is naive and innocent. When Buu's released, his first victim is Babidi's right-hand man, Dabura, who he turns into a cookie and devours. Majin Buu's first true battle is against Vegeta, who blows himself up in order to destroy Buu, but fails. He is then challenged by Goku who uses his new Super Saiyan 3 power to dominate much of the fight. However, Goku retreats from the battle after telling Buu of an even stronger fighter that will soon challenge him. Later on, Buu kills Babidi, and befriends a human named Hercule Satan, and a puppy which he finds and heals after he'd decided to go on a killing rampage. After realizing that the puppy liked him, Buu names the puppy Bay (Bee in English). Despite Buu's sudden change of heart, two gunmen destroy his house and attempt to kill Bee and Hercule. Due to his rage at the gunman, Buu's anger manifests itself in the form of another Buu ("The Buu of Pure Wrath") or "Evil Buu".
After a quick battle with the superior Buu of Pure Wrath, Buu is turned into a piece of chocolate and devoured, and the two combine to create Super Buu. Super Buu then tracks down Piccolo. While Gotenks is training in the Room of Spirit and Time, Piccolo tries to buy Gotenks more time by stalling Buu. He tells Buu that there are plenty of humans left on Earth to kill, knowing they can all be revived with the Dragon Balls. Impatient to fight Gotenks, Buu fires a large-scale genocide attack wiping out the remaining human population on Earth with the exception of the Z Fighters. Piccolo then leads Buu to the Room of Spirit and Time. Gotenks and Buu then battle, however, the battle ends in a draw when Gotenks defuses. When Buu escapes the room, he uses an attack to turn most of the Z Fighters into sweets. Shortly after, he is then faced by Gohan, who using his new hidden powers, is easily able to thrash Buu around. Buu then escapes from Gohan. When he returns an hour or so later, he absorbs Gotenks and Piccolo and gains a vast amount of power, enough to overtake Gohan. Gohan is then saved by his father Goku, who plans on fusing, but it fails and Gohan is absorbed by Buu. After absorbing Gohan, Buu is confronted by the fusion of Goku and Vegeta, Vegetto. Even after absorbing Gohan, Buu is no match for the power of Veggeto and is easily fought without much effort. Veggeto then allows himself to be eaten by Buu, so that he can save Gohan, Piccolo, Son Goten, and Trunks. Inside of Buu, Goku and Vegeta de-fuse and are successful in finding the others as well as Good Buu. Vegeta then rips the Good Buu out and as a result, Super Buu reverts to his purest form, the original child state called "The Buu of Pure Evil" or "Kid Buu". Right away Kid Buu uses a large energy bomb to destroy the Earth. Goku and Vegeta then battle Buu on the world of the Kai's. Even using his Super Saiyan 3 power, Goku is hardly able to damage Kid Buu at all. Eventually, Vegeta steps in and he too is no match for the power of Kid Buu. Later on during the fight, Good Buu is spit out by Kid Buu and he joins the fight, barely giving Goku enough time to gather the power for a Genki Dama (Spirit Bomb). Goku then launches the bomb at Buu, completely destroying him for good.
Upon the request of Goku, Buu is reincarnated in the form of a human named Uub, who is trained by Goku to become his successor, and who eventually merges with the Good Buu in Dragon Ball GT to counter threats such as Bebi, Super 17 and Omega Shenron.