Although ganondorf does out prioritze mario within certain arials, this match shouldn't be all that bad at all really unless you aren't considered that great with mario.
Fireball can gimp ganny and stop most of his important approaches. His weight makes him easily absorbed by jabs, which means you can do some pretty effective jab canceling combos. You can mini cg him with the f throw at lower percents, utilt can rack up nice damage. FLudd works wonders on ganny for a FIHL or straight up gimps, cape can screw his slow attacks and seriously gimp his recovery. Dair works wonders on gannondorf due to his height when you time it with effective FH or SH. Bair and uair chains work on him just as effective if you exploit how quick they are, oos with nairs to rush, shield dashing or perfect shielding to upb. Blah blah blah.......
As long as a mario can stay nimble, quick and active into avoiding ganons range on his usmash, jab, ftilt, fair, and dair, and bair this match should be cake. Mario has everything in his arsenal to counter ganon if you play smart. If you play into ganons metagame, you could turn it over into his favor since he can potentially KO mario within pretty amazing percentages. Watch out for his bair, and avoid trying to out prioritized ganons uair from above unless you throw a fireball.
Don't get me wrong, if played properly, ganondorf is really a force to be acknowledged. However, a smart mario mainer shouldn't be worried about him unless you aren't really good with mario.
-65:35 in mario's favor, without a doubt...
