Ganondorf has the best edgeguarding capabilities in the game hands down, but the reason for it is his aerials, most notably fair and reverse uair with their massive hitboxes and power. Dair, bair and choke are harder to land but will score a KO at virtually any %.
Ganondorf is probably bottom mid tier if the tiers are to be top, high, mid, low and bottom. Only with customs I'd dare to consider him high, because his recovery becomes excellent meaning he can actually live to high %s much more often and kill ridiculously early.
Let's go over his edge things real quick:
Bair - Good priority. Getting hit with it off stage kills most the cast at 60%, or sends them out too far to recover, or guarantees a low recovery. He can also do 2 from hanging from the edge and get back, covering direct and low options. Further, it's easy to hit after a ledge trump.
Uair - Kills later then bair for the main hitbox, but the back hitbox (second half of the move, at the feet) works like it did Melee: Won't outright kill, but forces a low recovery for most the cast. It's also easy to hit the weaker hit on edge trump.
Fair - Wizard Kick Cancel > Fair can work on some of the cast, netting early kills. Like, 50% early kills. That said, a solid Fair hit will kill earlier then Bair, but it sends them higher, so they can recover high or low.
Dair - Sourspot kills at about the same as Bair. Sweetspot (aka most of the move) outright kills, or causes a telegraphed recovery. You can Dair again, assuming they have a vertical recovery. If not, enjoy your free stock.
Utilt - Unconventional a bit, but it's hitbox is huge and lingers for a few frames. I list it because of it's trap potential and because it's strongest hitbox is a shield-break 100% of the time. Forces certain get-up options from the ledge. Ex: If they stand, attack, or roll on stage, they get hit by it when spaced well. They either have to jump, drop-jump, or just drop to avoid it. It also heavily punishes anything that doesn't sweetspot.
Really, I think Ganon will be a solid High-Mid, as customs will help him out a lot, a practiced Ganon will completely shut down most non-invincible recoveries, and the requirement to get reads on everything will become lessened as his Metagame, and approaches, develop against the entire cast.
Plus his Upsmash is godlike. 99% sure it gives Kicking Leg and Head invincibility on start-up. Don't quote me on it, because I haven't directly tested it. Just an observation in 1k or so Ganon matches.