Going to respond to Jimera0 here
Firstly, Zoroark, what is its purpose?
Simply put, what Zoroark has over any sweeper in the game, as its ability, Illusion, which allows it to masquerade as basically any pokemon in your party. Therefore, in order to use Zoroark effectivlly, its illusion ability must be abused in the team, I don't care how but it just has to be abused, otherwise there are far better sweepers / cleaners etc etc that you could use.
O.k, thats out of the way
Zororark on a defensive team will often result in Zoroark under-performing. Semi Stall teams might be different, I don't know, however I do know that in a pretty defensive team that Katakiri has posted, Zoroark is not being used as well as it could be. The reason for this is simple, defensive teams are built around taking hits, healing off the damage and stalling out the opposing team. Zoroark cannot do this as it has the defences of paper. This is, however, not the route of the problem. In order for Zoroark to be used effectively, it has to masquerade as a pokemon, if it has protect, this (in order to avoid making it blindingly obvious what you are pretending to be) forces you to often pretend to be a pokemon that commonly carries Protect. Zoroark can pretend to be Nidoqueen all it likes, but the moment I see it use Protect (which is a very unusual move to see on a Nidoqueen) Im going to be suspicious. Not only that, but Protect on Zoroark serves no purpose if you are pretending to be Nidoqueen, you just admitted that you are a Zoroark, rendering illusion pointless. If you don't use protect, you can abuse your Illusion for longer, but in that case, why are you using protect over another move like Sub, NP, SD, or Sucker Punch.
If, on Katakiri's Team, you are matched up with a Volt Turn Team, and you decide to lead with Zoroark matched up as a Ferrothorn. You are met with a Rotom W, Rotom W Volt Switchs as your protect, and then you go to Nidoqueen. This, in essence, tells me two things. Firstly, you had a free turn on Ferrothorn to set up Stealth Rock (which would hamper my Volt Turning plan), but you didn't, instead going to the (slightly riskier move) of bringing in Nidoqueen, which you then have to switch back out for fear of Hydro Pump. Logically, staying in with Ferrothorn would have been a better move unless you were a Zoroark in which case it explains and obvious switch.
tl:dr, if I see a "Ferrothorn" switch out of a Rotom W that is (apparently) locked into Volt Switch, against a Volt Turn Team, why would I switch out of something I wall, unless I was a Zoroark.
This problem is only increased if the Volt Turn Team leads with Landorus (most do and heck, after seeing a ground type ready to block Volt Switch id prolly lead with Landorus to be safe), and you lead with your Zoroark disguised as Ferrothorn. I U-Turn, you Protect and suddenly, you are in a shit position. In a normal situation, against this (probably) Scarf Landorus locked into U-Turn against a Ferrothorn there is ZERO Reason to switch out. You have a free turn to do whatever, AND you force the landorus to take IB damage upon U-Turning. However, on Katakiri's Team, you have a Zoroark, which HAS to switch out now, and therefore makes it obvious that your Zoroark is pretending to be a Ferrothorn, making it harder for Zoroark to get that surprise kill.
The problem does not stop there. Against any half decent opponent, running a defensive team draws out the length of the game, the longer the game goes on for, the harder it is for illusion to be maintained, and the less likely it is that Zoroark can nail that kill with Illusion. Furthermore, as you are pretending to be a Ferrothorn, you are limited in that your actual Ferrothorn, cannot switch in and take a Volt Switch, without revealing that what is Zoroark and what is the pokemon it pretends to be. In this way, by using a fully defensive team, you are actually making it easier for your opponent to quickly realise what Zoroark is pretending to be, even what Zoroark actually is (ie the fake Ferrothorn or the real Ferrothorn). At this point, Zoroark becomes an average sweeper, thats fast, hits decently hard, but lost the main perk of its ability, the main reason for USING it. At this point, you had to ask yourself, why am I then using Zoroark when I could be using something like MYSTIC Gar which can Scout as well as Zoroark, hit as hard as Zoroark, switch in easier than Zoroark, be faster than Zoroark, and can spinblock where Zoroark cannot and suddenly Zoroark becomes an inferior option.
So I guess I am saying, a defensive team has a much harder time at keeping Illusion active, in which case you are better off using something else that can take out what needs to be taken since, as I pointed out, keeping Illusion active is one of the only ways Zoroark can get that kill, and defensive teams fail to do this well enough.
With the bulk of the argument out of the way lets move on
Why not Protect?
Basically because it encourages defensive team mates to further the illusion (so as to prevent making it obvious what you are, so as to get that extra kill with Illusion) which in turn encourages a more defensive team, which in turn makes it harder to keep Illusion active.
Offensive Teams and Zoroark
Zoroark works much better on an offensive team. Offensive teams do sometimes include pokemon that can take hits, but primarily, they are offensive, and aim to finish a game as quickly as possible (certainly more quickly than a defensive team). it is, however, easier to keep Illusion active since you disguise yourself as a sweeper, and can hold back that sweeper with little disadvantage since, sweepers often hang back towards the end of the game so they can sweep later in the game when counters and suchlike have been removed. The faster pace also suits Zoroark as it gives your opponent less time to figure out what Zoroark is pretending to be if you sac occasionally to get things in for free (which is a common practise on an offensive team).
Why a Boosting move.
Example: I have a team with Zoroark, a Scarf Rotom W, and a Heatran. I disguise myself as Heatran, (not saying this is wise, its a rough example). My opponent has a Gyarados, and I managed to bring in Rotom W safely on Gyarados. I can Volt Switch on Gyarados, threatening a KO so my opponent brings in Ferrothorn, and I bring in Zoroark, disguised as Heatran, which can threaten to KO Ferrothorn with Fire Blast. My opponent, needs Ferrothorn alive, if it faints to a probable Heatran, Rotom W can cause massive damage to his team, he also needs it alive so he can set up Stealth Rock to guard against the powerful Volcarona I have on my team. There is a possibility Zoroark is Heatran, however, if he mispredicts and it is, actually a Heatran, he loses the game, if its a Zoroark, I could flamethrower anyway and win the game, and so, my opponent switchs out to a Gyarados, ready to wall a Fire Blast, set up a Substitute, Dragon dance a few times and sweep. Instead, he is faced with a +2 Zoroark, which can now crush him with a Dark Pulse (letting Heatran become a dominant force) or he can let something else take a hit which is fine, but w/e I still do massive damage or pull off a kill and can switch out.(even assuming I miss a KO a +2 Zoroark is hitting mighty hard) so job well done. If I get the KO then good shit, I got the free kill with Illusion and have a 90% Zoroark ready to kill shit.
Even if Zoroark did NOT find the time to Nasty Plot, its no big deal, unlike Protect, I am not forced to use it (when if you don't use protect you basically make it less useful) and I am not missing out on anything, as I still hit damn hard even without a nasty Plot boost. Simply put, if I get an opportunity to Nasty Plot then great, if I am pretending to be a pokemon that can Nasty Plot (or Swords Dance) then my Illusion is intact and so it works much better, even if I don't get to fake Illusion (by pairing with with something that doesn't get NP like Heatran) who cares, Im a +2 Zoroark with a free attack. If I don't pull off the Nasty Plot, then its no big deal, since its a free moveslot anyway.
Sorry if this is a bit of a wall of text, I did shorten it quite a bit as I think I went into too much detail. Anyway, this is, basically, why I feel that Zoroark should be on an offensive team, which Protect is less suited for over a more offensive move.
