Both Gengar and Zoroark get destroyed by Scizor's Bullet Punch. Also, Gengar is immune to Spikes because of Levitate and Zoroark isn't and since they're pretty popular right now, that would give it away. You should probably just go with Infernape since everyone is going to switch their Burunkeru into it and you can easily get a Nasty Plot up as they switch in and fire off a Dark Pulse for the KO.
Since Infernape can still learn Nasty Plot, Flamethrower, and Focus Blast, you should be able to keep the disguise up until you actually take out something with Dark Pulse. By that point, you've probably weakened or severely weakened their main Infernape counter.
Copying something that normally wouldn't be too threatening to some Pokemon, like Burunkeru itself, could be useful since Zoroark can just hit any Nattorei or Erufuun that switches in with a Flamethrower.
@The Enemy: Why are you running 3 STAB moves? Sucker Punch and Pursuit should be enough to take any Pokemon out and you just get walled by Steels even easier.