Here are Celebrity Mii QR Codes from the official Tomodachi Life website:
How would you like to play videogames with Christina Aguilera? Or sing karaoke with Shaquille O’Neal? Well, you can. Or at least, your Mii can, when you scan the QR Code patterns below and import these celebs into your Tomodachi Life game.
I’ll also take this time to link a great link from tumblr
http://tomodachiqr.tumblr.com/ – A blog dedicated to posting Tomodachi Life QR codes, If you see one of your QR codes on here please tell me so I can give you credit.