Mr. Buu's History
Majin Buu Saga
After taming the innocent Buu, it seemed that the world is saved by Mr. Satan. All is well until the two gunmen Van Zant and Smitty arrive with the goal of taking on Buu, and they shoot Bee as he is playing with Buu. This causes Buu to become more enraged than he has ever been, but this anger is quelled by Mr. Satan's disposing of the two gunmen and taking Bee back to Buu to be healed. The situation seems fixed as Buu rebuilds his house in the shape of Bee and Mr. Satan resumes his maid tasks. Buu now seems fully changed, playing with Bee and even asking Mr. Satan to sit and eat with him. Mr. Satan even destroys the fake pictures of Buu defeated that he had taken. This lasts until the gunman who shot Bee returns and shoots Mr. Satan in the chest. Buu is able to heal him but the pain of losing his best friend is so great that he struggles to control his anger. Finally, Buu loses control of his anger, and splits into Good Buu and Evil Buu. The evil leaves Buu in the form of a giant cloud taking most of his power with it, and Good Buu watches as the cloud takes form and becomes Evil Buu. A battle soon ensues between the two Buus, the Evil Buu dominates over the Good Buu. Good Buu is ultimately turned into chocolate and devoured, causing them to re-merge into Super Buu.
Though Super Buu is almost pure evil, Good Buu is still able to affect his actions slightly, preventing him from attacking Mr. Satan, Bee, and Videl on multiple occasions. He is later removed from Super Buu by Vegeta, and once the power of the Kais was removed from him, Super Buu reverted to the insane creature "created" by Bibidi, Kid Buu. Although Good Buu is no longer connected with Kid Buu, his presence alone prevents the other Buu from attacking Mr. Satan and Bee on the Sacred World of the Kai until he is spat out.
Good Buu is extremely pleased to see Bee and Mr. Satan are still alive, and then steps in the fight to defend Mr. Satan, and even though Kid Buu is far more powerful, he is able to land a few good hits on him due to his increased strength. He holds Kid Buu off while Goku and Vegeta ready the Super Spirit Bomb to defeat Kid Buu. Good Buu and Kid Buu battle ferociously, neither one of them backing down, with both Buus performing many techniques, such as the Multi-Form, Chocolate Beam, and more, but Kid Buu is clearly stronger, toying with Good Buu during the fight. After a hard battle, Good Buu is defeated by Kid Buu and presumed dead, so Vegeta battles Kid Buu while Goku readies the Spirit Bomb. The Spirit Bomb is finally formed after much delay, but Goku is unable to launch it due to Kid Buu holding Vegeta hostage.
Kid Buu prepares a final Planet Burst attack to kill Goku, when suddenly Good Buu appears again, not quite beaten yet. He and Mr. Satan rush into the battle, as Good Buu tackles Kid Buu, causing him to throw the attack without aim and misses, while Mr. Satan rescues Vegeta after Good Buu orders him to do so and gets him to safety. Goku throws the Spirit Bomb and after some struggle, the monster is finally defeated and the universe is saved. After the battle, Goku uses the Dragon Balls and wishes for no earthling to remember the havoc wreaked on the world by Majin Buu. In addition, in order to ensure that Buu not unleash a similar horror to Kid Buu again, Mr. Satan also forbade Good Buu from either getting angry ever again or at the very least not unleash his anger. Soon after, Good Buu is given the name Mr. Buu, and joins in the celebration of his evil counterpart's defeat at Capsule Corporation.
God of Destruction Beerus Saga
Six months after Kid Buu's defeat and being erased from the Earthlings' minds, Buu interrupts Mr. Satan's press conference at the Satan House furiously stating he was hungry. Without having a clue who Buu is, Mr. Satan took advantage of this and told the world that Majin Buu is a space soldier that went to Earth to be trained by him. After storming out, Mr. Satan leaves his conference to calm Buu down and give him a massage.
Buu attends Bulma's birthday party on a cruise ship. Buu starts to eat all the food before the party starts and Bulma gets angry over this. Mr. Satan tells Buu that Bulma has a massive feast specifically for him and that he needs to wait. Buu continues to eat throughout the party. When Beerus is on Earth, he is interested to try pudding which Buu had enough of. Beerus asked for at least one to taste it but Buu refused to give him one, angering Beerus. Mr. Satan tries to tell Buu to give him one but Beerus and Buu blasted him away for interrupting. Buu and Beerus faced off: Buu gave hits to Beerus but they simply didn't have any effect on him. Buu was tossed around by Beerus' speed and was blasted into the ocean. Buu tries several times afterward to hit Beerus but continues to get taken out. Buu later watches the battle between Super Saiyan God Goku and Beerus.
Golden Frieza Saga
After Frieza's revival, he states King Cold forbade Frieza from challenging two warriors, Lord Beerus and Majin Buu. Upon hearing from Sorbet that Goku beat Majin Buu, he decided to train to obtain his Golden Form. When Mr. Satan and Bee left the house to attend an emergency press conference, he passes by and says goodbye to Majin Buu, who, at the time, was reading a Nekomajin adaptation of the tale of Uroshima Taro. When Frieza arrives on Earth, Buu is sleeping when he is needed. While Goku and his friends were away, Buu and Mr. Satan were taking a nap in their mansion when they were unaware of the Earth exploding due to Frieza blowing it up. Mr. Satan, and presumably Buu, were killed until Whis undid the event with his Temporal Do-Over technique so that Goku can kill Frieza once more. Buu later attends the feast thrown by Bulma with her family and friends.
Universe 6 Saga
Buu is chosen by Goku to take part in the tournament between Beerus' team and Champa's team. The day of the tournament, Majin Buu is taken to the Nameless Planet along with his friends in Whis' box. After two hours and forty-five minutes, they arrive on the planet. As soon as they get there, the written test to participate in the tournament, requested by Vegeta, begins. Buu ends up falling asleep during the exam, automatically failing it by default. Since he failed, he is not able to participate, so he sits with his friends and watches the first battle between Goku and Botamo.
Buu finally woke up after the tournament was over and after Zeno showed and left and apologized to Mr. Satan for not being able to grant his wish. Buu later went with everyone else in the Cube and got to see Super Shenron before Beerus made his wish to make Champa's Earth just as hospitable as his.
Copy-Vegeta Saga
Buu joins in on another part. This time, he is ensured by Bulma that not even he can finish all of the food by himself.
Universe Survival Saga
Buu participates in Zeno's Tournament of Power as part of Team Universe 7. Universe 7 is matched up against Universe 9 in a standard 3v3 tournament-style match in the first round, and Goku asks Buu to fight with him and Gohan. Buu, along with Mr. Satan, travel to Zeno's Palace with Supreme Kai, Kibito, Old Kai, Beerus, Whis, Goku, and Gohan, and the entire team meets with Universe 9's team. They are transported by the Grand Minister to a tournament ring in an unspecified location, and Buu is matched up first to fight Basil (though he fell asleep during the explanations and had to be woken up by a chocolate bar). When the match began, Basil immediately assaulted Buu with a variety of attacks. Buu lays on the ground but then proceeds to grin and laugh, getting back up unharmed. Saying he wants to play more, he takes several more attacks and gets a hole blown through him. Assuming Basil has won, Roh begins to gloat to the annoyance of Sidra when Buu jumps back up and regenerates himself.
After doing so, Buu learns Mr. Satan was almost killed during Basil's last attack. Buu, now furious, stops playing and begins to fight seriously, dominating Basil, battering him around and throwing him clean out of the ring. The Zen-Ohs however, aren't happy with the fight ending so early and want it to continue until they're satisfied. Knowing Basil is outclassed, Roh throws him a drug which causes Basil to power up and appears to defeat Buu, bombarding him with dozens of Ki blasts. Buu immediately pops out of the rubble of the arena completely unharmed and claims to be stronger than Basil before unleashing a full power Kamehameha, winning the fight and nearly killing Basil. Having been declared the winner, Buu hurries over to Mr. Satan and heals him. Proud of Buu, Mr. Satan hugs him and calls him the best. Buu, having fulfilled his end of the deal, is now given his reward for fighting: tons of food.
Later, when heading to the Lookout to ask for Android 17's location, Goku finds Buu training, having even slimmed down. They decide to have a sparring match, which Buu easily wins. However, unfortunately for Goku and the others, Buu falls into a deep sleep and will not wake up for months. Desperate, Goku has no choice but to take drastic measures and ask Fortuneteller Baba to allow Frieza back into the world of the living for one day so he can compete in the tournament.
