It blows at top level. Puff's aerial mobility alone shuts Ganon down unless you're constantly getting small reads to maintain excellent zoning and stage control. Then of course there's bair. Bair, uair, and ground game are your best friends. Do whatever you can to get damage on her, the entire matchup is neutral game. NEVER get greedy, but you have to go in at some point. Just be really selective with your approaches. Tricky wL's, edge cancels, empty shorthops, shield drops, pivots, fp uair oos, safe dtilts, and auto-cancels are among the better ways to create an opening. Both high and low ftilt should be used more than in other matchups.
She can freaking crouch under anything, be careful when going for a grab if you think they expect it. She can crouch under the entire wizkick sometimes and rest at will. Dthrow to uair/bair at low%, and fair starting around 50ish but always space the **** out of fair after a dthrow, she can rest out of stun in time.
If it's not hbox, and you don't break any major rules, definitely a doable matchup despite being one of Ganon's hardest.