Asriel on 10 December 2014
Captain Toad.
He'll add a Captain Toad skin (or even character) to Mario Kart 8, random item/weapon unlocks in Hyrule Warriors, Captain Toad trophy/assist trophy in Smash, and have some kind of impact in Treasure Tracker itself. Maybe you can save 'ghost' times to the Captain Toad amiibo to take to your friend's house for them to race against.
