Might I suggest the following set?
Zoroark @Dark Jewel
Hasty(+Spe; -Def) - 20 Atk, 252 S.Atk, 236 Spe
Ability: Illusion
- Pursuit
- Sucker Punch
- Flamethrower
- Focus Blast
The reason is because Zoroark´s entire design revolves around deception, trickery, making the opponent believe in something which is not. Therefore, if you´re not using a NP set, a hit-and-run strategy suits Zoroark perfectly. The main difference between using Zoroark and Weavile is that Weavile is expected to do something like Pursuit or Swords Dance, for example. Zoroark will always be in disguise and should not be expected to do the same role, thus earning you free kills when it "shouldn´t".
Now for each choice:
- Dark Jewel might sound odd. But, being a hit-and-run threat with the surprise factor, once Zoroark does its first Sucker Punch or Pursuit, its cover will already be blown for the time being. So, its first Dark attack should hurt as much as possible to ensure the kill on whatever it attacks. Dark Jewel allows for that without taking away its freedom of choice.
- The EV spread is just a personal choice of mine, as some may argue that attacking order is irrelevant on a trapping Dark 'mon. Still, Zoroark´s speed tier is a nice one to have and outpacing Garchomp is important to me. Also, providing power for its special attacks is also necessary.
- Pursuit and Sucker Punch are the crux of the set, allowing it to revenge-kill Ghosts and Psychics with 100% efficiency if your prediction skills are good, which is what Zoroark should be doing most of the time(Shandera, Latios and Espeon come to mind).
- Flamethrower and Focus Blast compliment the set by allowing Zoroark to kill the likes of Tyranitar, Nattorei and Scizor with ease.
Also important to note is that Zoroark´s partners should focus on conceiving his own nature while attracting 'mons it´s likely to kill and scarings 'mons that give him trouble. Ghost-types and Fighting-types are always nice disguises for Zoroark, as both inhibit the appearance of Fighting and Bug-types(Zoroark´s weaknesses) while attracting Ghosts and Psychics for the slaughter. Additionally, Normal-types can force switches on Ghost-types, allowing a free Pursuit on their @$$e$. Gengar, Blaziken, Lucario(especially after Draco Meteors) and the likes usually provide the opportunities Zoroark needs so much. This Zoroark should only be used if your team has trouble against 'mons such as Latios, Shandera, Starmie and such.