Dtilt becomes especially useful against this fat boy. It's got better range than warios melee attacks, and you can sneak it in underneath some of his aerials before they make contact with you. Swoops reverse buffering thread works here nicely in theory insofar as the dtilt is such a fantastic move with which to buffer all your aerials. Since Ganon's height is often a problem vs characters like wario who have huge lateral aerial movement and strong aerial attacks, the dtilt doubles as a crouch in the sense that your height is essentially halved, but it also puts a hit box out in front of you so that if a wario tries to come in too quickly or too low, he eats the boot. Bear in mind also that (and some of this may sound ridiculously obvious, but IMO salient nonetheless) you can crouch into a dtilt, crouch out of a dtilt, shield out of crouch, crouch out of shield, etc. That is, if you're aiming to poke wario's aerial approach with your dtilt and you miss, don't necessarily stand up and try something else. Try staying crouched, try crouching til wario is real close then perfect shield the attack directly out of the crouch in order to create a gap of a few frames to transition from defense to offense.
Also, the bite isn't as effective against ganon as phantomx says above. The scenarios described above only become effective and consistent against a player who doesn't know how the hell to space himself. Phantom, (or anyone else) does wario have super armor on the tail end of his bite? are there any open frames (lag?) if this is the case, then bite - which is described above essentially as a punishing move - becomes a move to be punished instead.
No doubt about it, this can be a rough fight for ganon, but it's not the large disadvantage that both match-up charts have agreed upon. Spacing is the name of the game here, as per usual.