magic

You need a Wii U. To TAKE screenshots... 3DS-- Open the Rosalina menu with L, Down on the +Control Pad, and Select, then select the option. Wii U-- Press TV and Left on the +Control Pad in Aroma.

You install a plugin that lets you take screenshots by TV + left on the dpad but I would change if if you use the gamepad as a TV remote as shortcuts on the TV button tend to not make the TV remote menu not show up sometimes.