"can actually set up on a lot of Pokémon"
I can see out of the S- and A-ranked Pokémon that Volcarona could set up on: Aegislash, Celesteela, Ferrothorn, Scizor, Venusaur, Heracross, Cresselia, Porygon2 and Zapdos, but only if there are no Stealth Rocks on Volcarona's side. The other Pokémon...