Shouldn't evil buu be able to use an attack from a foe he kills? Like from the candy ray, first person (after each respawn) he kills, he gets one of their attacks. Krillin's distructo disc, piccolo's special beam cannon, cell/goku's kamehameha and so on. He did it to gotenks, piccolo, fat buu, and gohan, but the added cloathing could be left out and when fat buu transforms he isn't the discoloered evil buu, rather after he got absorbed.
After all, once evil buu was released, he absorbed fat buu right away. Plus, if more transformations were added, then evil buu would have to absorb a fat buu to transform, which is what happened. Team play with good and evil would stop this dead, cause what team member is gona stay fat buu long enough to make someone else super buu? Though a good point is that cell can transform with no #17. Still, attack copy would not really overpower buu too much, just give him some nifty new tricks. A good example of this would be Battle of the Mellenium's Mega Man X character. When he killed an opponent, he got one of their moves (like superman's heat vision). Just a thought...