Pokemon Name: Regigigas
Move 1: Facade
Move 2: Spore
Move 3: Dragon Tail
Move 4: Knock Off
Item: Toxic Orb
Ability: Poison Heal
Nature: Jolly (+Spe -Spa)
Poison Heal Regigigas has received a lot of popularity in the ladder, but most choose a terrible moveset. This Regigigas has the niche of blocking spores, sporing threats that lack an ability/move that can stop it, Facading, causing enormous damage and Knocking off Eviolites or other useful items from the foe. Dragon Tail allows you to not only do a little bit of damage to Giratina-O, it also allows you to abuse BW's new sleep mechanics by phazing foes that you put to sleep.
It struggles against Magic Bounce Skarmory, Magic Bounce Dialga and Magic Bounce Escavalier (You can knock off their item at least) and also against opposing Poison Healers.