There's an awesome
article by harsha2014 that is both very recent and quite thorough. Gastrodon, Blissey, and Breloom are some of the Pokemon that instantly come to mind. Gastrodon stops Volt Switch while Blissey can pass around paralysis and take hits well. Rotom-W has almost nothing on Breloom, which can then proceed to Bulk Up. One of my personal favorites is Landorus (mentioned by
NixHex), who resists U-turn, is immune to Volt Switch, and outspeeds all Volturners with a Choice Scarf bar other Scarf Landorus. Best of luck!