I don't know about everyone else, but I feel that Ganon is a significantly fundamentally stronger character than Zard for a few reasons.
1. Variety of hitbox area coverage. Ganon is able to quickly put a huge hitbox in basically any direction relatively quickly, at pretty much any time. Zard is a lot more limited in terms of the directions he can quickly stick big hitboxes out. Notice how quickly Ganon's uair, nair, and bair come out.
2. Ganon has a larger grounded threat range, and more threatening approaches, due to dash attack. Not much more needs to be said here, ganon's DA is goddamn insane.
3. Consistent grab followups. If Ganon grabs you, you're dead. If Zard grabs you and you DI properly, you're probably fine.
4. Safe landings. Zard is extremely vulnerable in the air (particularly in front of himself), but Ganon can just stick out a fair and become unpunishable by anyone within like 10 feet in front of him. In addition, the mixup of side B right before landing makes his landing game extremely robust and difficult to deal with. This means Ganon has pretty good means of circumventing (or even
capitalizing upon) positions that would ordinarily be considered disadvantageous.
5. Usable defensive options. By now, we all know about Zard's rolls. Ganon is also much skinnier and has a far superior spotdodge.
Charizard obviously has strengths too, but IMO they're much more difficult to capitalize upon against strong opponents. He has a very high DD speed, but his dash attack sucks and he has no other means of projecting threat at long range while dashing. His ftilt and jab are godly, but have high endlag and are very easy to punish if shielded or CCed (except ftilt at max range). Nair's range is huge, but Zard lacks Puff's aerial mobility and is huge and easy to punish if he whiffs.
That's just my opinion as a fairly biased player, though.
@Umbreon thinks Charizard is my best character (including my Bowser), so it may be worth taking that with a grain of salt.