>>18832782It's actually one of the best checks to Azumarill if this is accurate.
Not only is it immune to one STAB and resists the other, but its faster so it can burn it easily. Keep in mind this is also pretty much the only thing Volcanion can do to Azumarill.
252+ Atk Huge Power Azumarill Superpower vs. 252 HP / 252+ Def Volcanion: 102-120 (28 - 32.9%) -- 87.6% chance to 4HKO after Leftovers recovery
252+ Atk Huge Power Azumarill Play Rough vs. 252 HP / 252+ Def Volcanion: 57-67 (15.6 - 18.4%) -- possible 8HKO after Leftovers recovery
I ran max hp and def because 2/3 of Volcanion's weaknesses come from physical attacks, and should Rotom-W or any Electriic type switch in you can just go for something else.