Rotom

With the transition from DPP to BW, the Rotom formes traded their Ghost typings for that of their respective signature moves, leaving Rotom as the only Electric / Ghost Pokemon. Its unique typing grants it resistances and immunities to common attacking types such as Electric, Fighting, Bug, and Ground. This in turn gives Rotom numerous opportunities to switch in and pose a nuisance, which it excels at thanks to moves such as Will-O-Wisp, Trick, and Volt Switch. Rotom's stats don't disappoint either: it has relatively good Speed, decent Special Attack, and moderate defenses. Altogether, Rotom is a great Pokemon, and with proper investment can shine in a variety of roles, both offensive and defensive.