Many gamers want a classic controller to play their games. Despite the fact that WiiU already have a classic controller, a company from Japan thought something better, to connect a Dualshock 3 or 4 on Wii U.
This adapter from Cyber Gadget, can be connected into WiiU's controller and gives one USB port. In this port, you can connect your PS controller. So simple.
You can buy it from Amazon of Japan for￥2,894, or €20.8.