Buu Forms explained

[Perspective]

In order to understand the different forms of Majin Buu and how they relate to Kid Buu, the colors and appearances of the Boo forms should be analyzed.

Kid Buu was the being Majin Buu and he was evil. The being Majin Buu is pink. Kid Buu was pink which indicates that he was Majin Buu.

Kid Buu absorbed the Southern Supreme Kai and became Buff Buu. Buff Buu was Kid Buu with the Southern Supreme Kai absorbed. Buff Buu was Majin Buu and he was evil.

Buff Buu absorbed the Grand Supreme Kai and became Fat Buu. Fat Buu was Kid Buu with the Southern Supreme Kai & the Grand Supreme Kai absorbed and with the evil essence of Kid Buu still inside his body but not having a major influence anymore. The main difference between Kid Buu and Fat Buu was that Kid Buu was evil whereas Fat Buu was not evil and majorly influenced by the goodness of the Grand Supreme Kai. Thus Fat Buu was a different person than Kid Buu as they had different personalities but Fat Buu was still the being Majin Buu. The Southern Supreme Kai and the Grand Supreme Kai who heavily influenced Fat Buu himself would be absorbed inside of him and the evil essence of Kid Buu would be floating around inside of him somewhere, maybe in the form of a cloud.

When Fat Buu expelled the evil essence of Kid Buu that was inside of him, there was then a Good Buu and a gray, skinny Buu. The gray, skinny Buu was the evil essence of the being Majin Buu; the evil essence of the being Majin Buu took on the form of the gray, skinny Buu because “Buu was evil”, evil as in a noun, and the gray, skinny Buu was a realization of that. The Good Buu was Majin Buu but he was not evil. Both the gray, skinny Buu and Fat Buu differ from Kid Buu because Kid Buu was the being Majin Buu AND he was evil.

The gray, skinny Buu absorbed Good Buu to form Super Buu. Super Buu was the gray, skinny Buu with the Good Buu absorbed. Good Buu after being absorbed by the gray, skinny Buu was still pink as seen when Goku and Vegeta were inside of Buu’s body. Super Buu was the gray, skinny Buu, just with the Good Buu absorbed & altering his appearance which is why he looks different from the gray, skinny Buu. This means that when the gray, skinny Buu absorbed the Good Buu, he himself became pink. So Super Buu was the being Majin Buu, which is indicated by the fact that he was pink, and he was evil. When the Good Buu was removed from Super Buu, Super Buu/the gray, skinny Buu became Kid Buu and Super Buu most closely resembles Kid Buu. This would suggest that Super Buu actually was Kid Buu amped up by the Good Buu. Super Buu was tall either because of the Southern Supreme Kai inside of Good Buu or because Super Buu was the gray, skinny Buu himself and the Grand Supreme Kai’s plumpness + Southern Supreme Kai’s muscularity was what made him muscular but not as muscular as Buff Buu.

[theherodjl]

Welcome to the forums.

Your analysis on Majin Boo is pretty much the gist of it, except I disagree on a few things.
1. Fat Boo ceased to be Majin Boo period the moment that Pure Evil Boo split off from him, he was just an incarnation of Dai Kaioshin with the general anatomy of Majin Boo.
2. Super Boo was not an amped form of Kid Boo but rather he was the physical embodiment of Majin Boo's evil having been powered up, possessing the strength of South Kaioshin but also being hindered by the purity of Dai kaioshin within Fat Boo.
3. Once Fat Boo was ripped out of Super Boo's head is when Super Boo lost all connection to everything he had absorbed and so the evil of Majin Boo forcibly reset itself, reverting to the original form of Pure Boo aka the real Majin Boo.

Otherwise, your theory is pretty much solid on everything else.

[sintzu]

This is how I see things :

After the 2 kais are absorbed Fat Buu is the solo Buu and only becomes 2 when he's VERY angey so there was never a kid Buu living in him until then. Vegeta points out at the end that if his dog dies, he could get so angry that another Kid Buu is born which proves that he was only one and split out of anger.

When Buu turns into Kid Buu Vegeta asks why he didn't turn Gray which proves that it wasn't a plot hole so I think the Gray Buu was a weak Kid Buu but after absorbing Fat Buu for awhile, he got his body and shape back to normal.