You don't need a sensor bar for the Gamepad.
Seriously though, the Pro Controller isn't compatable with games there's no reason for it not to be compatable with?The most unelegant approach here by Nintendo. It's a controller stew.
Edit - also, what's the deal with the sensor bar? Can anyone who owns a WiiU confirm if you need one for the Gamepad or is it just for MP when you use WiiMotes?