I can't say I'm all too happy about BP even being considered. Smith and BKC have basically said everything i want to say regarding this, but I still have some points. First, prediction is a players biggest advantage against a BP team. save those focus punches for when they matter, whirlwind on the turn they baton pass. Make sure you have attacks that can severely damage Smeargle on most if not all Pokemon, the turn it ingrains (if you've been playing well) should not have a sub active.
Anyways, I'm not a fan of the usage of BP teams because they dictate the flow of battle so much. the non-bp player is just attacking and hoping for luck to be on his side.