Alright. Only watched the first video, but here's what I've got for ya:
Too much Down Aerial. It's good, but it's not the solution to everything.
Weird timing for Up Bs...that seemed to work. Dunno if that's because you're good at that thing, he's bad at moving, or if it's...dunno, just plain weird.
Weird timing/choices for moves. You had Sheik on the ledge at one point just waiting to die, and you did a neutral air. Finger slip or something? Also, a lot of Over Bs don't really pan out in the end.
Down B is a great finisher move if you use it sparingly and when they don't expect it. Use it once a minute, then it's not going to help you much.
Aha! That's what it is! You're not SHFFLing. You're just SHing, doing the move, and L-Cancelling. The FF part is ESPECIALLY important for Ganon, especially in his Fair.
Parts of your Ganon remind me of mine, early on. Keep up the good work, mate. And my apologies for having to play against a Sheik.