I use a Mischievious Heart Riolu with Overhead Throw and Copycat. The purpose is to use Overhead Throw, which almost always goes last. Then Copycat, which copies the last move used and has +1 priority from MHeart, selects Overhead Throw, giving me priority phazing. On PO, you can only use this once, and you can't chain together multiple Copycats. But I posted this question in the research thread, and it has been confirmed that you can chain together multiple Copycats in-game in BW. We should probably get that fixed.