My top 5:
1. Garchomp/Altaria Swarm
Can outspeed zekeels and can take many easy prizes. It can use Terrakions to beat Darkrai varients.
Not to mention that its incredibly consistent.
2nd- Zekeels/Eel variants
Without junk arm, Darkrai loses some consistency. Eels can take out Darkrais with Terrakions. Darkrai can still outspeed Eels, so they could be switched.
3rd- Darkrai/Hydreigon or other variants
Fast, hard to Ko w/o Terraks and can demolish most decks. I placed it lower b/c it loses Smeargle, Shaymin, and Junk Arm, cards that boosted the decks greatness in this format. Its ability to abuse Max Potion makes it seem invincible.
4th- Empoleon/stuff
With its built in draw and quick attacks, it could easily be a top contender.
5th- Quad stuff
Slow, but consistent. Hard to Ohko.
I believe that Entei will rise in play.
Edit: I can't believe I forgot Terrakion EX.....nvm Terrakion will rise in play because it ACTUALLY has acceleration. Terrakion can deal out hits and take hits as well. Problem is, like regular Terrakion, you still need 3 Turns to set up, and by that time, your Terrakion EX could be Koed.
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This may sound weird, but I think Durant could b used in BW-on. I understand that it loses many Extremely Vital cards in the rotation, but with the Juniper abuse and "slower" format, it may do well. But, it will not be Big tourney worthy b/c it can lose easily. I just wanted to say it isn't exactly dead BW-on. After all, 4 catcher, hammers, and Hooligans could really tick people off.
Accelock will b ok, but it loses Twins and is inconsistent. Mew EX would work better as the attacker, but the deck would die to Mew2 EX if damage is miscalculated and the KO goes into the opponents turn.