Chrystina
07.09 💜
One user on Tumblr appears to have confirmed that the mobile home villagers can be adopted, but not any special villagers via Splatoon/Zelda/Monster Hunter amiibos.
Proof: http://68.media.tumblr.com/7c25f013d4a4eb058fb4b97846eceafc/tumblr_og6k1ibGF81u6c1cxo4_1280.png
Now the user was using a save editor so it might have been a glitch, but attempting to get Felyne adopted didn't work, and I believe Felyne was added in via the same save editor.
So I think the only new villagers that cannot be adopted are Felyne, Wolf Link, Ganon, Medli, Epona, Cece, Viche, and Inkwell. Unclear about the Sanrio 6 or 7-11 villagers Filly and the hamster.
Well, I do know they can be adopted to move in from their mobile homes. What I mean is that they cannot be traded (sold/given away/etc), they simply go into the void once they decide to leave your town. So having them ranked within the tier list would be pointless, since this list is to rank which villagers are most sought-out after to buy/adopt.
Hope this clears things up, unless I misunderstood your post D: