This does not matter if you are logged in to another account or not. If the Wii U game has been purchased by the pervious owner, you can download it for free!
How cool is that? Escpecially if they have downloaded the New Super Mario Bros U.
There are a few indie titles you could get, you could grab the totally bonkers, pyro maniacs dream – 2D Boy's Little Inferno, the amazingly beautiful Trine 2 and of course the fab multiplayer Chasing Aurora.
As they are indie developers though, you may want to purchase the game anyway as they rely on the funds to make more games and live off.
- Second Hand Nintendo Wii U Consoles Lets New Owners Download Games for Free (news.softpedia.com)
- Want Free Wii U eShop Games? Buy a Second-Hand Wii U! (godisageek.com)
- Used Wii U Consoles Allow You To Download Someone Else's Nintendo eShop Games For Free? (mynintendonews.com)