Proof that I can vote :
I'm voting for Ban Shadow Tag ability !
The main reason is that here (and only here) we do not have Team-Preview before starting the fight, without his Gothitelle is much too powerful since it is not anticipable!
Its not for nothing that on Smogon this pokémon is classified in the tier UBER with Shadow Tag & PU without.
• For me the only condition to make it playable is to set up the Team-Preview as in any other pokemon games for years (official or not) with the team-preview the PVP fights here will be much better for all World!
And for those who say it's simple to Revenge-kill Gothitelle with a Pokémon DARK:
1) A good pvp player will always wait for the moment to send Gothitelle when the opponent has nothing more to counter it.
2) We do not all have a Tyranitar, Weavile or Scizor for revenge-kill in our team, there are more than 600 pokemons in this game and we have 6 in combat, the chances of having one of these pokémon Thirds) are really thin.
In conclusion: It would be high time to set up the Team Preview in this game !
Thanks !