Splatoon allows for motion control in Battle Dojo with a special code and unique setup (second player)
Splatoon features a 1-on-1 local multiplayer mode called “Battle Dojo”. One player handles the GamePad, while the other uses a Wii U Pro Controller, Classic Controller, or Classic Controller Pro.
As it turns out, the second player can actually enable a motion control setup thanks to a special input. With the unique code, that person can use a Wiimote with the Classic Controller or Classic Controller Pro to turn on motion controls.
As outlined by Nintendo in a Tumblr update:
One of our scientists has made a rather stunning discovery! From early reports, it appears to be a means of adding motion control to the controller of the player playing on the TV screen in Battle Dojo. On the controller selection screen for Battle Dojo, press and hold down on the +Control Pad, press and hold B, and then press ZR and ZL.
It seems a Wii Remote Plus is necessary to perform this incredible feat. This technique also appears to be possible when using a Classic Controller or Classic Controller Pro! When using a Wii U Pro Controller, first press ZL and ZR to select that as your controller, and then press the 2 Button on the Wii Remote Plus to activate it.
