Mario Kart 8 is an curious example to cite. The game was sold with a free download of another game - and choices included many top tier first-party titles. That's a very unusual tactic. It's a great game, but I'm sure this will have been a big driver for sales.
I wonder if the tallies for the other games (e.g. NSMB-U, Nintendoland, Z:WW) include those sold as a pack in, or free download?
http://en.wikipedia.org/wiki/List_of_best-selling_Wii_U_vide...