First of all, on his customs, Little Mac's recovery is better against edgeguarding because of Grounding Blow. It actually gives him the ability to vary his recovery. Aside from that, he doesn't get much, and it actually becomes harder for him to recover from F-Tilt.
As for the matchup, bear in mind that Little Mac is the one that's approaching, since Ganondorf outranges Mac. Space him out heavily. While Little Mac has fairly long range for a small character, he doesn't outrange Ganondorf.
Secondly, the moment you land a hit on Little Mac, Flame Choke. Flame Choke over and over and over again. Literally nothing Little Mac can do will beat it. Airdodge? Gets hit anyway. Counter? Flame Choke is a grab. Aerial? Don't make me laugh. If he tries to cheese you with midair counters, you can delay your U-air and F-air or even go for an Aerudo. Counter is the only real winning proposition for Mac in the air, so even if you guess wrong and he doesn't counter, you still have a chance to hit him.
Lastly, F-tilt. Yes, this move gets its own spot for this matchup. Ganondorf can boot Mac into a position where he is forced to recover from like, 40-50%, and at that point, Mac is doomed completely. Even if he counters, he'll drop too low to get back. Speaking of counter, due to Mac's awful aerial acceleration, if he tries to counter you to recover, you can literally do nothing and laugh as he falls to his doom. F-tilt is so good that you should almost never use F-Smash even. Use it off of reads of course, but other than that, F-tilt is the only kill option you'll need.
The most important thing about this matchup however, is that Mac basically can't take a single hit against Ganondorf. Put simply, if you land a hit on Little Mac, he's dead. Once he's in disadvantage against Dorf, the only way out should be death. While it is very difficult to actually land that hit due to Mac's speed, all you need is one read and he's done.