I would like to point out I have put plenty of work into building the best possible stall teams- no matter what you do they be outclassed by offense in BW2. I agree that a stall team can be good on it's own, but it will be clearly inferior to BW2 bulky offense / offense no matter what you do, even if you put a Choice Scarfer on it to revenge threats. Dual Screens offense would be an extreme case of BW2 offense eating stall but without weather control (even with against some mons) you may as well give up vs Torn / Thund / Keldeo / any physical attacker in sun etc. It's very easy to set up hazards and threaten a team offensively but not to threaten another defensively. It's not impossible to beat another team by stalling but it clearly won't work as often as a good team should.