>>526924857
I believe they could make him have a knack for learning magic, but I don't think he'd learn some of Buu's most broken powers, or at least, I don't think Toriyama would, since Buu's powers and durability are so broken that he'd be a perfect team player, and that's why Toriyama always writes him out.

In U6 tournament, he could advance up until fighting Hit since he has no stamina to worry about and he's stronger than everyone else, and against Hit, he could be a little of a nuisance since assassination attacks wouldn't really work (Though Hit would still win since he'd overpower Buu). And during Black, (specially) ToP and Super Hero, he would casually solve the stamina issues everyone else had with his healing... Hell, in Daima Dende could've healed everyone, once he was aged back, but Toriyama either forgot, or ignored it for drama.

In Neko Majin, Toriyama talks like Uub is very strong too... But Uub would be really difficult to write around if he were to get the same powers as Buu, otherwise he'd be that guy who gets knocked out so fights have stakes.