First off, I would like to introduce myself as a somewhat competitive player. My PS usernames are isaac.ramen, REAL RYDER, and per sé. Back in December, both isaac.ramen, and per sé were all in the 2000s. I consider myself to be a pretty decent player, with a good understanding of the metagame.
1. Is Baton Pass (with specific reference to full Baton Pass teams) a problem for the development of the metagame?
Not exactly. However, I find that baton pass teams require no skill to run, and ruins the fun of competitive battle. Now, I know I used, 'fun' and 'competitive' in the same sentence, but I consider myself to be a somewhat competitive player, usually playing around the 1600s-1700s (on REAL RYDER. Obviously this fluctuates if I lose games). However, I find it as a illegitimate strategy for winning, and ruins the game for people who are trying to win with real teams. People claim that there are ways to get around Baton pass, but in my opinion this requires other players to run specific Pokemon to counter baton passing teams, such as Bisharp. Will this over-centralize the metagame? If this continues, yes. It frustrates me that I spend time building a quality team, and watch it get destroyed by a cookie-cutter team that really takes very little skill and prediction to play effectively.
2. If so, what elements, in particular, do you think are pushing Baton Pass over the edge?
The biggest issues for me are Magic Bounce Espeon, which obviously cannot be banned, as it is perfectly viable on a regular team, and Pokemon like smeargle, who can set up ingrain, and prevent phazing. I know smeargle is with ingrain is less common, but when it has happened to me, it really got me upset. I didn't even know that you could not roar out a Pokemon who had ingrained. Scolipede is pretty annoying too, with decent defenses, with speed boost, having something Ninjask never had.
Should any of the above Pokemon be banned?
Of course not. There would have to be an arrangement that would obviously have to be made. All are relatively easy to deal with on their own, but when put together with baton pass are a huge pain in neck.
3. Would you support a blanket ban on the move Baton Pass?
Perhaps. Sure, a boosted dragonite, or a boosted Kyurem Black would be pretty threatening, but can be combated.
4. Would you support the introduction of complex bans (like Pokémon X+Pokémon Y on the same team)? Feel free to suggest more forms of complex bans, of course.
Baton pass is a cool move, sort of like volt switch, and u-turn, that gives switch initiative, but avoids trapping moves, like pursuit. I used to run Baton Pass on my Celebi last generation to bait a Tyranitar's pursuit, and and BP into my Terrakion to get a +1 Justified boost. However, I think trying to come up with a combination ban of sorts is hard to me, and should be left to other users with better judgement than me.