Since Meloetta got an announcement out of the blue last week, how about we take a look at what it can bring to your team? Meloetta, unfortunately, is a Pokémon that looks amazing on paper... until you look at the fine print. Indeed, the problem that will likely screw it over is the part where it will always revert to its Aria form whenever it switches out or at the end of the battle. As a result, if you want to use the Pirouette form at all, you'll have to sacrifice a moveslot for Relic Song, which performs the form change, and a turn to use it. EVERY SINGLE TIME YOU SWITCH IN. And both form's stat spreads are polar opposites, meaning that moves that are useful in one form are worthless in the other - much like Zen Mode Darmanitan, which no one ever uses because of that. Shame, because if you could stay in Pirouette form as long as you want (like how Shaymin can keep its Sky form)... well, I'd smell a suspect test. STABbed Close Combat off 128 attack and 128 speed? YES PLEASE.
So now that we've established that, how about the Aria form? Well, the direct competition comes from Jirachi, given the typing and ability. Problem is, Jirachi's typing is infinitely more useful, both offensively and defensively, it's much bulkier physically, and it has a crazy array of moves to abuse Serene Grace with. Meloetta... hits harder and is more specially defensive (arguable because of the typing, though). Serene Grace almost seems like nothing but a filler ability. Overall, it has a few interesting assets, but I have a hard time seeing it break into OU.
By the way, fun fact: Relic Song is the only move in the game that has a sleep chance as an added effect (20% when factoring in Serene Grace). This could potentially lead to all sorts of crazy hijinxs about the definition of the Sleep Clause. But I'm not too worried about it, because even if you wanted to use Relic Song for the damage and sleep chance, guess what? It also happens to be the move that triggers the form change, making it completely useless if you want to remain in Aria form (and you should)! So if for some reason you want a Normal move (which DOES get STAB to be fair), Hyper Voice is definitely your best shot.
On another subject, I've been thinking about what BW2 could do to help Kyurem become better. I know we're all looking forward to the alternate forms, their new stats and their new moves, but I've been wondering lately about the regular form itself. Remember when Shaymin-L, which used to be horrendous, obtained a few new moves only the Sky form could learn as hand-me-downs, as well as move tutors? It actually became OU for a little while. Could the same happen with Kyurem? Judging by the nature of the alternate forms, it's not impossible for them to get moves like Fusion Bolt or Fusion Flare, which regular Kyurem would enjoy very, very much. Maybe even Bolt Strike and Blue Flare? It's only wishful thinking at that point, but a guy can hope, right? It's almost certain that the alternate forms will get Cold Flare and Freeze Bolt, but these are Sky Attack clones, and unless the forms get a new ability that cancels charge-up turns they're not going to do a damn thing...