Speaking of Superheavies and their viability, I seriously recommend that anyone who who doubts Charizard's usefulness to PT's team, or just wants to watch a good set in general, watches Wishes's set against Light. Charizard put in some serious work.
https://www.twitch.tv/videos/407043022?t=07h49m01s
Anyway here's the stuff I got out of this match up.
can wrack up damage extremely well, and getting those combos started isn't too tricky either. Squirtle's neutral is probably the strongest of the team's in this match up, as he's too good at zonebreaking to reliably keep out with Ivy. It is worth noting that Squirtle's even with Squirtle's small hurtbox and good aerial acceleration he still struggled in disadvantage, especially since Fox has the speed to punish Withdraw as long as Light was prepared.
can't zone or land that well in the Fox match up, but Wishes did show that Ivysaur still has her uses. Fox is at his most vulnerable when he's offstage or at the corner, which is where you could see Wishes switch to Ivysaur the most. Even if she was least important Pokemon in this set Ivysaur definitely still carried her weight on the team. But now let's talk the character I'm most excited to bring up.
showed exactly how powerful he can be at the ledge or in advantage. Even a fast faller like Fox struggled to land against Charizard's amazing ground pressure and OoS. Zard's fantastic out of shield game came into play here, not just because of his lightning-fast Up Smash but because of how rewarding his throws are. Wishes also showed constantly just how dangerous Charizard's Bair is in every game state but especially in advantage, killing Fox at an impressively low 65% by calling out a high recovery and later at 72%. It's also worth noting that Wishes would sometimes switch to Charizard while he was cornered as Ivysaur in this match up.
And yet despite all Charizard did in this set there was not a single Flare Blitz kill. This match really affirmed to me that Charizard who is amazing at carrying momentum or making comebacks, and isn't just some silly Flare Blitz bot like so many people think he is.
Anyway, I still think Fox is a losing match up for PT overall but if this set shows anything it's far from undoable as long as you know understand the value of corner pressure.