Gameplay element. By plot standards, he becomes stronger, what with being able to use the powers of darkness.But Sora becomes piss weak in anti form.
But there's still the fact that Sora has defeated stronger enemies than either of them.Sure he can move quickly and deal alot of fast hits but so can Squall and Cloud.
The ability to change into Forms come from clothes, but his abilities in those forms come from the power in his heart. Besides, it isn't that different from Cloud getting his powers from Materia, Squall getting his powers from Junctions, etc. Sure, it's where they get their power from, but the strength of their abilities from using Magic from Junctions and Materia is their own.Also his form powers come from his clothes.
They weren't chosen by the keyblade. That itself proves they aren't strong as Sora, because the power of one's heart = everything.
Limit Form.Also his form powers come from his clothes+merging with a party member, so its not really his power.




