Just a quick note… you can tell the Wiimote to report, and tell the Pi to read, the state of the accelerometer on the Wiimote so you can work out its orientation.

Here’s a code snippet from the article:

#set Wiimote to report button presses and accelerometer state 
wm.rpt_mode = cwiid.RPT_BTN | cwiid.RPT_ACC 

Read the full Cambridge University article here