Ironically Stall struggles the most with Kyurem out of any archetype. They don’t run bulky steels that can pivot around it like Gambit, no offensive mons that can threaten Kyu out, no AV Gking, nada. However Stall definitely has ways around it.
One thing I found was that Mola with 144HP/112Def/252SpD can tank one Specs Freeze Dry at full and tech Mirror Coat to wipe it off the face of the Earth. There was also a Rachi Stall knexhawk ran which checks most Kyurem variants nicely. The set variant they have to watch out for is DD and hope it’s not carrying Freeze Dry.
Specs Kyurem is very annoying as it has only one switch in (Blissey) but there are ways to play around it, with and without tera. The much bigger issue are the mixed attacker sets (NMI Kyurem got popularized by that Probopass HO RMT and is good outside of just stallbusting.) Body Press Kyurem is a mid ladder classic, I remember people complaining in the stall discord about it before the Volc suspect.This is just straight up wrong. Nearly all stall players of note disagree with you given nearly every stall player voted DNB for the Kyurem suspect test. There are clear outs, sometimes with Tera if need be. You just have to figure out what set it is, which there will be room to do given how fat most stall teams are.
Volc's ban has been pretty bad for stall, not only because it had a good matchup into the moth itself, but because the presence of sweepers that you can't afford to give a turn or two pushes the metagame towards a faster state, which benefits stall. The classic mons that 6-0 stall on team preview like Ursaluna + Wish, Haxorus, or Hoopa-U all tend to be very slow and have terrible matchups into non-fat teams. Even outside of those, there are plenty of mons that are absurdly good against stall and aren't liabilities into everything else. Mixed Kyurem sets were the catalyst for this conversation, but stuff like Primarina, Boots Pult, Woger, Taunt/Knock Goon, and SD Scor are everywhere and while you don't just instawin on load they are independently great mons who put a ton of pressure on stall.
Stall teams are adapting, for example there's a lot more usage of Pex as it matches up well into both Prim and mixed Kyurem, but opens up holes in your team elsewhere. It'll probably take some time for the metagame to shift and people to cook up some new strats, but at the moment it definitely feels like the weakest main archetype.