Due to its lack of defense and sp. defense I thought maybe giving my Zoroark a Focus Sash would be a good ideia, but at the same time giving it a Life Orb would really make this thing a threat to many Pokemon.
Zoroark @ Life Orb/ Focus Sash
252 Sp.Atk/ 252 Spd/ 4 HP
I'd say Focus Sash just so you could set up nasty plot. If you want to run Life Orb I would rather have U-Turn than Nasty Plot. And if you decide to go with Focus Sash, make sure you have a spinner.
Now that I think about it, with the plethora of hazards this gen, i'd say you could go either way.
You should go for the Focus sash. Thanks to the focus sash, you can set up a nasty plot, and with that major speed, you should be able to take down some foes.
Focus Sash is generally an item most Pokemon would prefer not using, with the exception of random leads like Infernape, Endeavour Mamoswine etc. etc.
Zoroark would prefer the extra power of Life Orb in my opinion, rather than Focus Sash. You're basically using a copy of the Old Gen 5 Smogon Zoroark set, which also utilised Life Orb or Leftovers.
focus sash. why: because if you were holding a life orb, your HP would go down when you want to preserve your energy.
life orb. why: because all your moves are not effective against your opponent's Pokemon & this will power it up.
it all depends if you want HP or power. it is your Pokemon. you can do what you want with it.