Although you’ll be able to play the 3DS version of Hyrule Warriors on any system, only the new 3DS will actually let you view the game in 3D.
This news was originally posted on Japanese site 4Gamer, before being translated by Perfectly Nintendo. It comes from an interview the site conducted with Yosuke Hayashi, the producer of Hyrule Warriors on both the Wii U and the 3DS.
Aside from the news that the 3D effect will only work for players using the new 3DS, Hayashi also stated that DLC codes for unlocking Toon Link, Tetra and the King of Hyrule in the Wii U version of the game will come packaged with the 3DS version. He also stated that the game will have amiibo support.
Hyrule Warriors Legends will largely be the same as the Wii U version, and will come with all the DLC released so far. It is due for release in 2016.