Okay, my Volcarona didn't turn out so well, so I'll try a move set for Zoroark, which goes after coverages and sweeping a bit more than just stabbing and stat boosting.
Zoroark
Illusion
Item: Life Orb/ Wise Glasses
252 sp. atk/ 252. speed
Timid Nature
~Dark Pulse
~Extrasensory
~Flamethrower
~Focus Blast/ Nasty Plot
Okay, here's the plan. Use Illusion to make Zoroark look like a Gengar, because I garuntee you that no one is going to use a Fighting or Bug move on him. The may use a Psychic, Ghost, or Dark move, which works out well. If you're running Nasty Plot, use it now. However, when he's attacked, Zoroark will reveal himself, and you'll just sweep from there with your decent coverage and boosted speed and sp. atk. Flamethrower should help take out any evil bug types, and Extrasensory should deal with fighting types. Dark Pulse is a stab move, which is cool but doesn't get very good coverage. Now, you may skip Nasty Plot and go with Focus Blast because Hydregion and Heatran can just kinda laugh at you you'll have to switch out, meaning a good Nasty Plot set up went to waste. The Life Orb is a great booster, but it hurts you, too, which I don't really like. However, I guess in Competitive play you take one battle at a time and being injured doesn't mean too much. Wise glasses will boost all of your moves, but not as much as Life Orb. Aslo, if you think Zoroark's 105 speed is fast enough for you, you can switch his nature to Modest, but IMO his sp. attack is better of than his speed.