At a Nintendo developer roundtable this evening, Nintendo confirmed that there will be no inter-connectivity between their two upcoming Mario games—New Super Mario Bros. 2 for the 3DS and New Super Mario Bros. U for the Wii U.
Why not? Because, Nintendo say, the two Marios are being made by different teams. Each team has its own ideas of what to put in their game, and there are no shortage of ideas for them to draw from. Additionally, both games are being designed for two entirely separate systems, and the purpose of each game is to highlight the features of the system it’s on.
New Super Mario Bros. 2 for the Nintendo 3DS will be released on August 19th. Meanwhile, New Super Mario Bros. U will be released sometime this holiday.