EDIT: Apparently this post isn't clear enough but I'm pro-ban .-.
I really don't understand why people are freaking out over this. Since gen 3, there's been a sort of "gentleman's agreement" when it comes to Baton Pass: don't use it. This is something that has been going on since Smogon's inception. If you respect your opponent and want to represent your own skill in a match and not a team's effectiveness, you brought a normal team and not garbage like Baton Pass. It seems to me, a suspect of Baton Pass would just be putting into writing what has already been agreed upon for the last 4 generations: don't be a asshole and use Baton Pass. I'm glad that someone brought up Costa's match because if you look at the chat (and if you talked to SPL players afterwards), everyone was freaking out and furious with Costa for bringing the strategy. I find it hilarious (and simultaneously disgusting) that people can sit here and say that Baton Pass is a "playstyle" that requires "skill." Neither of those words should ever be used to describe Baton Pass. My thoughts on this can be broken down into a few main points:
It takes little-to-no skill to play BP
The skill level it takes to win with Baton Pass is minimal. You can't sit there and tell me that it takes skill to switch into Espeon on a lead Thundurus (or sylveon because guess what: it beats Thundy without BP :O a crazy concept, I know). It takes no skill to create a 50/50. People have been throwing around the idea of "predictions" as if they mean anything. Predicting is nothing. Prediction is just glorified guesswork. Sure, there might be situational pressure for your pressure for your opponent to make one more or another, but really it comes down to being right or being wrong. Baton Pass may have to "guess" what the opponent is going to do (although I don't really think this is even true due to the nature of Baton Pass eliminating the element of double switches or anything of the sort). Predictions=/=skill and anyone who says it does is kidding themselves into thinking that they somehow develop the ability to read minds the more they play Pokemon (hint: you don't). Rather, BP is more formulaic. Switching is taken out of the equation since BP gives the team switch initiative. If opponent brings out A, send out X, if the opponent brings out B, send out Y. Some might say that this is simply an element of Pokemon in itself, but BP doesn't have nearly as much pressure as a normal team when switching around. First, it gains Defensive boosts. Second, usually these are games without hazards, and if you DO set up hazards, you give the BP team more time to boost.
While not overcentralizing, it is an outlier in the meta
Baton Pass has no counters. Everything that has been mentioned in this thread so far can be stopped by something on BP. On the rare occasions when the opponent has something that might break Baton Pass chain (note: not the team, just the singular chain), there are easy fixes. Talonflame? Zapdos. Prankster Taunt? Mental Herb is your friend. Boosting sweepers is my favorite, because clearly you people have not heard about my friend Encore. Both Mime and Smeargle can carry Encore and it completely ruins any attempt to beat BP with your own setup sweeper. Even Mega Pinsir is beaten by Focus Sash Smeargle (Spore is also your friend). Now, this might seem like an exaggeration to some, and obviously no Baton Pass team (that I've seen anyway) has counters to everything. No team does, for that matter. But BP causes an unhealthy shift in the meta. It is, by definition an outlier. People can say it's overcentrailizing, but that's not true. It's an obscure threat, sure (well, except the top of the ladder), but that's exactly the issue. I personally believe that Baton Pass is too obscure to be given a serious thought in team building. Moreover, the checks that exist to Baton Pass are also obscure. Taunt Thundy is only used for BP and Deo-S. haze Quagsire only works on stall, and even then it has better things to use its moveslots for. Trick Sableye or Klefki is complete garbage. Talonflame doesn't even check BP so idk what people are talking about here ?_? Zapdos and Vaporeon easily set up on it. These things are not normally seen in the meta (cept Talon which is not a counter at all lmfao), and I don't think that they are within a reasonable margin to call it a "meta shift."
Baton Pass is, for the most part, reliant on matchup to win
You can say that Baton Pass can lose to regular teams, and I'm sure it has. But I doubt these losses were by normal means. Perhaps a crit or a critical misplay cot the match for the BP user, but there is almost no way outside of luck that a normal team (one that fits within the margin I talked about in the last post) can handle BP. Most games with BP are decided at team preview short of hax. This is clearly shown in the SPL match with Costa. He would have won without hax, with hax, he lost. It's really as simple as that. I have played BP. I have played against BP. I have watched competent players use BP. It is, in the hands of a competent player, an entirely matchup based strategy, with very VERY few things it doesn't match up well against.
tl;dr: we already have a de facto ban on it anyway, why not make it de jure? .-.