Coming from a Nintendo Life interview with Witch Beam's developer and co-founder Sanatana Mishra...

For starters we will definitely be supporting off-screen play and also the use of practically any controller configuration, Wii Remote + Nunchuck as a replacement for Keyboard/Mouse and the twin stick pads. GamePad specific elements are still a bit TBD as we need to be careful to avoid gimmicky tacked-on gameplay, so I imagine we won't be talking about them until much closer to the Wii U version's release.

Link