Squid Odyssey will allow cross download for the 3DS and Wii U.
The 3DS release of Squids Odyssey offers the Wii U version of the game for free on the European eShop.
This cross-buy feature is the first on any Nintendo system. Popularized with the "Cross-Buy" name on PlayStation platforms, cross-buy allows for the owner of a game on one system the ability to own it on another for free. In the case of Squids Odyssey, If you buy the 3DS eShop version of the game, and have your Nintendo Network ID linked up to both your 3DS and Wii U, you will receive the Wii U version of the game for free.