Testing ZSS stuff, just now finding out her dair has a sour spot. That's... neat?
I'm ballparking a lot of stuff here but ima give some approx numbers for how her chainthrows look on fox. I'm starting with DI away. Uthrow regrab stuff doesn't seem feasible until after 25, assuming DI away. That's the point where there's about 2 frames leniency, but that's also for multiple inputs so realistically we might not expect to see that kind of performance consistently for a long time, if at all. I'd give it more percent on that, like 35-40% before starting the regrabs tbh. Any other DI gives pretty easy regrabs after like 10% with just grab in place/turn grab, with utilt before that. The window definitely increases with percent, ending slightly after 100 (slightly after 100 is sketchy since fox basically has to fall into the grab since there's only like a frame where his fall overlaps the grabbox in hitstun). With no DI, and probably similar for DI in, the regrab ends slightly after 75%. Some half DI behind her could probably get a vertical angle which would end the CG a bit earlier. At the point where no DI/DI behind/anything besides DI away no longer allow regrabs, utilt's pretty easy to hit, you can even just position to land just the vertical hit to prevent wonky SDI from messing with the linking hit. And that vertical hit is going to convert VERY hard. So basically Fox's options are DI away until 100% and then get fair sweet'd/RAR bair sweet'd/upair'd offstage, or don't DI/DI in until 75% then eat utilt vertical hit into fair sweet/bair sweet/almost anything to send him offstage/possibly extend the punish further.
But there's two issues here. The starting percent is pretty high. Even TAS inputs can't get a DI away regrab below like 15%. And humanly, expecting regrabs below 30% is a tall order currently, and still tough long-term even when player technical skill will have developed to extremes. Factoring that in, ZSS has to build a lot of percent relying off tech chases, assuming she gets a grab, or find other ways to build that percent. Additionally, platforms. Those numbers were found just on FD, because platforms complicate things. Chaingrabs don't like platforms. That doesn't make the chaingrab useless by any means of course- it gives ZSS some CP pressure. Fox won't want ZSS on FD, GHZ, and to a lesser extent, SV. PS2 and DL also have more scarce platform coverage (they're pretty empty in the middle) than many other stages. But since I don't think most stagelists give 3 bans, ZSS is gonna get one of those lightly platformed stages guaranteed as a CP and likely PS2 or DL for the starter (especially if both are on the starter list, but having just GHZ SV and PS2 as starters would work). Of course, the existence of platforms doesn't negate CG's entirely- it's a positional issue, and CG's can happen briefly even on YS. So what's gonna matter for those stages where she's not getting more than 2 regrabs due to platforms is what she can do with platform tech chasing. Which I don't know lol.