Speed: Relativistic (Easily faster than Gotenks whose speed feat was calced at most to be half light speed, and much faster than the 5 digit hypersonic Cell)
Kid Buu: Solar system level+, (Going by Cell's statement from powerscaling, and easily stronger than Freeza who casually planet busts)
Fat Buu: Same as above
Super Buu (Gohan Absorbed): Potentially multi-solar system level by powerscaling
Kid Buu: Multi-planet+ (With regeneration can be much higher)
Fat Buu: Multi-planet+ (Not much different from Kid Buu)
Super Buu (Gohan absorbed): Star level+, possibly Large Star Level (By powerscaling off of Freeza)
Kid Buu: Lowest intelligence, mindless and only tries to kill
Fat Buu: Low intelligence, but able to copy attacks by seeing them just once)
Super Buu (With Gohan absorbed): Easily the smartest, has high intelligence because he contains Piccolo's intelligence.
Abilities: Regeneration, Candy beam, absorbsion, and Ki manipulation.