Pretty much anything you can find here or anywhere else works on the latest, just make sure if he intends to keep his console vulnerable that he blocks the updates because Nintendo is bound to put up one last fight before they move on to the NX.
Definetly Super Mario Maker, that's probably one of my most played games on the system. Splatoon is pretty fun, so is Mario Kart 8, and smash, and even though Mario Party 10 isn't the traditional Mario Party, I actually find it pretty fun. Yoshis wolly world is also a great platformer. However, one game I do not recommend is getting Animal Crossing: Amiibo Festival. I got the game at Christmas and was so excited, and it turned out to be a horrible game (And this is coming from somebody who loves Mario Party 10)