The entire Zoroark bluff usually lasts 1 turn only, 2 at the very best. You always want Zoroark to DO something, not just to basically be a carbon-copy of another Pokemon in your last team slot. When I was in a Double-Dragon craze, Zoro did perfectly disguising as Garchomp or Ononokusu (minus the Mold Breaker announcement when AxeFace comes in, but it didn't throw off as bad since Rivalry is kinda-sorta viable), using Swords Dance as they switched in something, and roasting Steels with Flamethrower or Sucker Punching their Scarfers. The idea is to use Zoro to clear the way for OTHER sweepers, not meld with something so perfectly in a disguise that you have 2 of the same thing.