>>20447566>as I've said before, you're playing by someone else's rulesPeople refer to smogon tiers even when not talking about 6v6 singles because it gives a rough indication of how good something is. If it's good in OU, and is not a wallmon like Chansey or Skarmory, it's probably good in doubles, too. There's a very large overlap, with the only exceptions being if it has things like Follow Me, Helping Hand, Wide Guard, Intimidate, etc.
Oh and Mega Lopunny is probably going to be very good in doubles, much better than in singles. The fast Fake Out, as well as the ability to Encore support moves and nail Mega Mom, is very good. It also gets Helping Hand, though I doubt it has enough room to fit it in, or other support moves like Charm/Baby-Doll Eyes and Thunder Wave.