Continues to here: https://www.furaffinity.net/view/41417296/

As an unstoppable monster that can't be permanently destroyed, Buu is basically the most overpowered person in the dragon ball universe, as a mortal. He doesn't get tired easily, he takes no damage, and he instantly learns techniques. Basically, he's all kinds of ready to ruin any other kind of fighter. Even immortals need rest occassionally.

When Buu fell asleep before the tournament of power, RIGHT before it, Gohan and Picollo decided that having Frieza join was too stupid, so they came up with an idea. They had to hide it from Goku, but carried the sleeping monster into the hyperbolic time chamber; waiting for him to wake up. A month's sleep is just a few hours in there.
Once the majin was awoken and fed EVERYTHING in the look-out, he was obliged to help Mr Satan and Goku in the Tournament. After all, it was fun.
With all of the fighters gathered, Goku, Vegeta and co. entered the tournament. Right off the back, they were ambushed by the trio-de Dangers and Universe 9. Knowing how dangerous buu was, Basil switched with Lavenda, who came swinging; poison litering the stage and wiping out several fighters, though he had to tone it back so that they didn't get a deadly dose. The mad wolf launched a cloud of poisonous haze, which rained down on the oblivious blob. Buu was immune to poison, and saw it as nothing more than a game. He couldn't kill him, but his techniques were very interesting. Buu was curious as to how the wolf made it rain... He may have been able to copy any technique, but biological ones could be tricky. So he used his special technique, launching a beam on the wolf when his gaurd was down. Goo immediately covered the wolf, turning him into a servant to buu as it took him over.

Lavenda's brothers were laughing at how Lavenda knocked everyone OTHER than Buu around, but they immediatealy yelledd in panic when their brother started working with the other Universe. Zeno was extremely impressed. He had JUST began to see fighting in a competitive light, and was curious as to how Buu would control Lavenda's body.
"THAT'S UNFAIR! THAT GIVES THEM ONE EXTRA WARRIOR!" The kai of that universe yelled.
"On the contrary... and using such techniques will entertain the Omni-king all the more." The Grand Priest said to the shocked Kai.
From that moment, the tournament turned to Universe 7's favor. With 2 invincible fighters; albeit one of them possessed by the other, they made light work of everyone. Anytime that they were nearly knocked out, they just extended their arms and grabbed the stadium, before coming back and returning the blow with twice the power.
When it was all over, Lavenda was a permanent servant to buu, and no more dangerous to universe 7 than a puppy. Buu's control made him act like a wild wolf, and his fighting style was just as hard to read as a wild animal. Universe 7 and a few extras that were "appropriated" to their cause won, as Buu took them over as well. Among them were Basil, Bergamo and ESPECIALLY Ribbrianne, who Buu fell in love with on sight.... though it was moreso a one sided marriage, on the condition that if Universe 7 won, they'd wish back her Universe at least.
Android 17 wished back everyone's Universe regardless, but the two were basically Universe-crossed lovers now. They were all released departed their separate ways, but the Trio-De-Dangers and were too far gone. They were the first who fell under Buu's spell, and begged to stay with him in Universe 7. Since Universe 9 was too happy about being alive, they didn't care. In their eyes, the three wolves were just to weak to have the right to return. They couldn't have been more wrong, and they returned to Universe 7; servants to Good Buu.
The Majin had other plans for them. Chocolate-y ones.