Yeah but if Arceus is running Choice Specs, which there is no reason not to, you can force a switchout and get stealthrock up. It's not a true counter, but it's a way to threaten.
I've been thinking about something else and I think Pokemon itself has been leaning this direction lately.
I would add a new feature: Training.
The basic premise being you can train a pokemon for something, like a status condition, or entry hazard, and they will deal with it better, but won't be immune.
I'm trying to make some for flinching, confusion, reducing damage from criticals, attract, and moves like follow me, but I can't think of anything that isn't RNG dependent.