Pokemon that would be better if there was no team preview

Mmn honestly the game did change a bit with the team previews. But see, when you mention Zoroark, it also makes me think that you could use the team preview to your advantage as well if you're not doing the full 6v6.

What do I mean?
Unless you're doing a Showdown or actually battling a friend on the game, usually you use only three or four out of the six you bring (varies based on what kind of battle we're doing) in the battle spot. Of course, people on the games aren't probably as keen on the Pokémon meta and strategies as people who use Showdown, however the preview could potentially trick the user to be prepared for the Zoroark and bring a counter (if available), while the trainer who brought the Zoroark not use it at all.

Just a simple thought.
As for teams that are truly affect by the preview, I'll have to think more on it. You've already mentioned the Zoroark, which was the first to come to my mind.

 

Pretty much the only Pokémon that got "nerfed" with the introduction of Team Preview is Zoroark, which would be too ridiculous without Team Preview. Not sure what set would used the most, but probably some kind of Anti-Lead with Taunt, or NP sweeper. While you can say that there were more Pokémon that got nerfed, but for the rest, it's more of a case of having their role/ability nerfed. Dedicated leads are not that strong anymore, and immunity granting abilities are now easier to play around, but the Pokémon itself weren't nerfed. You could say same to Zoroak and it's ability, but you have to remember that Zoroak, and it's pre-evolution Zorua are the only Pokémon with Illusion as their ability, and they have no other abilities to choose from.

 

If your looking at it as a Pokémon it self prespective , every Pokémon is stronger , it would also eliminate the thought of "Over prediction" since you dont even know what or when your enemy will send out another Pokémon , if they have it even , True that Zoroak is the only one nerfed , but team preview has also issued certain points

• Scardy cat Tactic , Your Enemy surrenders The instant he sees your 6 Darkrais.
• Over Prediction , To know what and which move to choose by planning when and why your enemy will switch
  
  There are many abilties Other than Move absorbing ones getting nerfed as well , like , Every ability ever?
  
  Knowing the Enemy's Moves are invaluable in gameplay itself , if there was no Team Preview on Pokémon showdown , Everyone would run Absorbtion sets.

DANG IT NOCTIS , I DIDNT WANT TO REMMBER THAT POINT IN FE FATES :.:

 

I wasn't into competitive battling in 4th gen, but right now I would feel like I prefer seeing the whole squad bc I attempt to read my opponents plays alot when I'm battling them and seeing their whole squad is big part of doing it.