>>38255800Toxapex was one of the few Pokemon that could come in on Pheromosa without immediately dying, so Quiver Dance + Z-Hyper Beam was a set devised to easily muscle past it. Phero was also super frail, but not die in one hit to any priority move frail, so typically Pheromosa will autowin the game after that, especially if it was Modest to get the SpA boost on Beast Boost.
You could also get a QD on some other specially attacking walls that can't quite punch through Phero's bulk with the +1SpD, or as another anon mentioned, hard reads. QD wasn't broken because it was consistent, it was broken because the few Pokemon in the tier that could even check Pheromosas other sets were turned into setup fodder.
