Okay, catching up on the thread: I'd personally prefer if we stick purely to our types, because that's a lot of the fun/challenge of it. We don't have to be an unbeatable, but I do agree that we still want to be a challenge. Maybe we could consider the "one off-type but on-theme" Pokemon thing for if a certain gym is consistently getting steamrolled and can't solve it within their type? Also, as for people building counter teams: I'm not sure how much of a problem we should expect. I mean, it takes some effort to build a proper counter team (IVs, EVs, choosing attacks, etc), so hopefully it shouldn't be an issue that comes up too often. And I hope we could take the kind of rough attempt of splashing a team of untrained Pokemon we're weak to against us. Also, I guess we should take a vote on Pokemon that Mega-Evolve into types that they otherwise aren't. I don't think there's any problem if they actually Mega-Evolve. And it looks like the ones this applies to are Mega Charizard (X), Mega Pinsir, Mega Gyarados, (Mega Mewtwo X but he's banned anyway), and Mega Ampharos. I dunno, my opinion is that most of those wouldn't make a dent anyway, but at the very least the Dark Gym probably shouldn't be throwing around a Gyarados without Mega evolving it.
Also, I still need a Tyranitarite if anybody has an extra through cloning or whatever. And I realize that we've set things up pretty quick, so maybe to be fair we could stick to Gym Leaders offering normal double battles (with options for other types like Rotation, etc if they want), and then I guess late-comers could double down on the types of people who absolutely don't want to do normal double battles. If everyone agrees to it of course.