Which brings me to my next point - while we can't know for sure what they'd nerf, we can do educated guesses based off of BSS and VGC
Assuming Zacian is in the games (ofc it'll be, pretty much guaranteed that we'll get all restricteds eventually), it's all but obvious he'll get some kind of nerf. The ability triggering "once per game" isnt as big as a nerf to be fair, even without the free +1 it's still a monstrous bulky behemot with Sword Dance.
What however I wouldn't be surprised happening is... more Intimidate nerfs.
This gen we already had a bunch of indirect nerfs to it: several abilities make you immune to it (notably, Inner Focus, which was already a very strong VGC ability due to fake out immunity), several of the new nonrestricted legendaries either ignore it (Urshifu) or get buffed from it (Zapdos / Articuno, tecnically also Enamorous). And it wasnt enough, cause if you saw Worlds, Incineroar still turretted at over 90% usage.
And... for the love of arceus I hope if they want to do more movexit they set on fire Ally Switch. Noone likes it. Not even me. Only reason we didn't see Ally Switch shenenigans in VGC is cause Calyrex, Groudon and Kyogre (at least 1 of them was in almost every team) all have Spread moves that don't care, otherwise it'd be 50/50s all over the place like it was in pre-restricted era.