Well, how much damage is it actually doing? 10 + 30 for everything on your opponent's bench? Unless your opponent is a ham sandwich like the guy in the ad; dropping Sky Field and dumping their hand onto the bench, they're probably going to be playing around Mind Jack. Even MRay, the eight-guys-on-the-bench deck, doesn't need to do MRay levels of damage to kill a stage one pokemon. Even Zoroark BREAK is going down to four benched pokemon and a Muscle Band. On the other side of the table, you're going to need an opponent with a full bench plus a Muscle Band to hit the magic number 180. Now, this isn't exactly easy for Night March or Vespiquen either, but at least those decks have control over their own damage output. All Zoroark can do is try to get value out of Target Whistle and hope the opponent has no choice but to fill up their bench, all the while weakening its own attack as it takes knockouts. You're dealing with other limitations, too - your attacker is a stage one, you rely heavily on DCE, and if all that isn't enough and the deck is still a major threat, the metagame will start shifting in such a way that Zoroark's matchups suffer.
Unless I'm missing something huge here, even if it weren't good policy in general to reserve judgment on this sort of thing, this is unlikely to be good enough to cause problems. I'm not even wholly convinced it'll be playable.