I've got fond memories of Four Swords Adventure on the GameCube, so today I was thinking about what a 2D co-op Zelda game on the Wii U could look like. One of the ideas I had plays around with time travel, with the player or players on the TV inhabiting the present while the player on the gamepad goes around changing the past to assist them.
You could even have puzzles that involved the player in the past opening time bubbles similar to the desert sections of Skyward Sword. Where the players in the present might see a crumbled bridge, the player in the past can open a time bubble that brings a structurally sound bridge from the past into the present. This concept could be used for all sorts of puzzles.
Anyway that's just my half-baked idea of what they could do. Do you guys have any ideas how a 2D coop Zelda game could work on the Wii U?