Hello, first thanks for your work as PvP council!
I will give my opinion about Kyurem in the current meta while it have some counter like Mega Medicham/Lopunny and many, I think it is not healthy for your meta right now.
-First of all : Freeze Dry, I dont think in your current meta it is good. Will use this examole for the future, while Azumarill was a "counter" (if you dont miss Play Rough) it is not anymore possible due to this move but like you mentionned the non item information can be crucial even If HDB is not in game currently you cant know the set of Kyurem in the game (SubRoost or Specs)
-Hail Def boost in the game, it is something more broken with the SubRolst set, just sub in front of a stall pokemon how cant break your sub, Pressure it ans you can change the whole game with.
I personally do not believe that kyurem is particularly broken or bannable at the moment but need to be in wanted list until more pokemon is added.