Can Wii remotes be used with the Wii U?

Yes, you can connect a Wii Remote to a Wii U. It's required for Wii Mode, and to play any Wii games that require it. Setting up a Wii Remote on the Wii U is done the same way you do it on the Wii - hold down the red buttons on the Wii U and Wii Remote until they connect.