I have been playing with Roserade latley.
Roserade/Choice Scarf
Timid
252 SpA/252 Spe/4 SpD
Sleep Powder
Leaf Storm/Grass Knot
Shadow Ball
HPFire/HP Ice
Modest is an option to seal the deal on the OHKO against Kyogre, but you really want this grass type to have as much speed as possible. As you can see, it's meant to revenge kill Kyogre/Groudon with it's powerful Leaf Storms. Wobuffet takes it down if it catches you locked into the -2 Leaf Storm, but what does it not in that situation. If you lead with it, you can hit Deo-E with a shadow ball as it taunts, then finish it off with it only have gotten SR up. Speaking of Deoxys, this is decent to revenge Choice Specs Deo-A with aswell. Shadow Ball hits quite a few ubers for super effective damage, so you can use this set to revenge kill weakened Psychics. Hidden Power Fire is if your opponent thinks he can switch Forretress or Scizor into your Leaf Storms, punish them accordingly. HP Ice is also an option, it will allow you to revenge kill a Rayquaza locked into Outrage (after you lose one of your team members, you bad player, you!) The main reason I am running this, is because it frees Darkrai up a spot and allows it to run Dark Pulse/Focus Blast on the sub-salac set. So your Darkrai isn't a sleep slave..
Decent coverage, a reliable sleep move, ability to switch into weaker special attacks (Choice Scarf Mewtwo's Aura Sphere is a 4HKO), and the speed that only choice scarf could provide to base 90s. It's worked out so far in my battles, but somone else could try this and give us their thoughts aswell.