Darkrai

With its incredible 125 base Speed—outsped by only a handful of Pokemon regularly seen in the Uber tier—and respectable 135 base Special Attack, this terror of twilight induces nighttime horrors throughout the land it travels. With Dark Void capturing opponents in its enveloping slumber 80% of the time and Nasty Plot raising an already impressive Special Attack, Darkrai is one of the most successful boosting sweepers in the Uber metagame. Darkrai's ability, Bad Dreams, deals damage to any sleeping Pokemon, allowing it to render opponents' Focus Sashes useless. On top of this, Darkrai's Dark typing grants it an immunity to Mirror Coat, allowing Darkrai to take on Wobbuffet extremely well.