ZSS isn't that nasty.
I believe she's got a CG on us from 0% to like 40%.
It is 0-69%, +regrab. Dash Attack Locking is also really nasty on Ganon because his recovery is awful. If you get locked, it sends you off the stage at a kind of weird downward trajectory setting up for an easy gimp. It isn't guaranteed, but Ganon's recovery is really predictable and ZSS has a pretty good edge game (not the best, but good).
Her disjointers aren't too annoying, except for maybe the gun.
The only attack she has that isn't disjointed is her jab. Which attacks are you talking about?
Anyway, a smart ZSS player knows that being aggressive vs. a solid Ganon is a good way to eat dirt. Thus she'll play very defensively and campy and vs. characters with bad grab range/no mid-to-long-range projectiles, this is very, very easy, and not because of side-b. Properly spaced, the disjoints on her tilts and aerials won't be punishable and are safe on block vs Ganon.
We've discussed this match-up a bit in the ZSS IRC (we have a few people in there who play Ganon for fun/secondary) and have it figured to be somewhere between 70:30 and 75:25 simply due to how limited Ganon's mid-range options are (rather, they are virtually non-existent) and because like most large characters, ZSS has a lot of fun comboing him in the air. And the chain-grab. And the lock. And the gimping.
As general as this sounds, your best bet is to try to focus on bringing the emphasis to the ground game and choosing stages that reflect that. ZSS doesn't do well on Jungle Japes because her side-b and up-b get screwed up by Brawl Ledges™. ZSS does really well on Norfair, on RC, and maybe on Brinstar depending on on how well the opponent does. I hear Ganon really likes Brinstar, though, so maybe you should try to CP that. Basically any stage that makes aerial combat very important will probably be bad for Ganon.
Hope I helped out.
The way to beat ZSS is to outzone her. She's crap at doing anything between her Forward B and Jab range.
It's true that ZSS is at a limited capacity at this zone range, but she does have a few tools such as bair, nair, and rising uair, all of which cover that weakness pretty well.
The real weakness is OOS options, so if you can get ZSS in a bad shielding situation you might be able to break it for a free kill.