Unfortunately, I'm basing my opinion on experience. G&W has huge disadvantages against Ganon. He's outprioritized, outranged, has less weight (too much less), has limited defense options, and he lacks a good dodge. Believe I have tried for years to beat with G&W various Ganon's I never can. No matter how much I try to adapt my metagame. Maybe it's purely because I suck, but I think that Ganon really is one of his worst match-ups. G&W is just a bit quicker, much longer lasting hitboxes, and a bit of an unpredictable recovery (but you have to sweet spot, else you are dead). Remember G&W has comparable power, but that's it. If you're playing againts a good Ganon, don't get your hopes up. Heck I even see the space animals, Shiek, Marth, Falcon, Puff and Peach as much better match-ups.