How about Adding a doubles teir to X and Y Even though they are not common they do exist. Just a mere suggestion but who knows 2v2 battles as some pokemon could use them and become better because that is what they are made for.
I would presume that a doubles tier would be created as the individual Pokemon themselves are distributed into tiers. PO is still in the process of tiering, so a doubles tier, I would assume, would be created once the initial tiering phase is complete.