Phazing is completely useless against Ranky. What does Roaring it out accomplish? You take a hit while using Roar (or Whirlwind) and it can very easily come back later. Magic Guard makes sure that it won't take any hazard damage in the process. It can just keep coming back and hitting your Phazer until it dies, and that's really easy to do when you're immune to all kinds of passive damage and have recovery to boot. (Hint: Switch Ranky into something like Blissey, which does absolutely nothing to it!)
Don't get me wrong, I don't find Ranky to be uber material... I just find it to be some REALLY good Pokémon. And a Pokémon which can't be countered by merely phazing it out.
Sleep Talk Phazing sets with Dragon Tail would work on him.
He's great against stall,but he doesn't make it completely unviable.
Give me PROOF that he will absolutely destroy all stall teams,then I'll believe he should be banned.