you just need to send a screenshot or something of the mii, tdc miis work just fine
this was from some shitty yt tutorial https://drive.usercontent.google.com/download?id=1rNiOGn5MkHMDuNNWVUOZO7Tiyl640vDM&export=download&authuser=0
comes with Tomodachi life rom and a fix for mii faces (it's the one I plan to use)
xavier renegade angel