We didn't really catch this with the New Super Luigi U stuff (if we did then I apologise and close this, did a quick search and didn't see it).
Before New Super Luigi U comes out (or on the same day), a patch will come for New Super Mario Bros U. This patch allows for two things
- Purchase of New Super Luigi U within New Super Mario Bros U. No need to go to the eShop
- Support for the games to be played with the Wii U Pro Controller