Not to say that I disagree with you, because Sora is wildly powerful, but we also have to consider that the enemies didn't exactly have have overpowered competition. While the final bosses often had to fight parties as opposed to single characters, it's not like the main characters themselves were all that powerful. I definitely would say that Sora > main characters, but I think he would have equal footing with Sephiroth and Kuja. Based on abilities, Sora has more than a fighting chance.
Now, let's not compare numbers. The poor boy has only got 120 HP and < 100 for Attack, Defense, and Magic. He doesn't even have Evasion or Accuracy! Holy Hell!
I don't see why not. Sora does have a double jump and several Up-B-worthy moves, such as Aero or Reflect. Dodge Roll or Quick Run could easily be Side-B moves if Sora is considered a "fast" character. Down-B could be Fire1/2/3, or Gravity1/2/3. Regular B could be Ice1/2/3 or some kind of mish-mash of a solo Trinity (or even Session) series of strikes.







