Thanks to the console's touch screen, the Wii U version of FIFA Soccer 13 will be a lot like the PS Vita version of the game. A variety of the game's features will be controlled through touch, including passing, tackling, and shooting.
For example, you can aim precisely where you want to kick the ball by first shaking the controller (or pressing L3) and then touching the spot you want to aim at. You'll also be able to defend using the touch screen, tapping on the player you want to control. You can then tap on attacking players to mark or tackle him. Once you gain control of the ball, you'll be able to pass by tapping at teammates.
Perhaps the most unique implementation of the Wii U controller is its free kick system. According to Official Nintendo Magazine (via Kotaku), you'll be able to lift the GamePad and look through the screen to aim the ball. "Basically, you are seeing it from the free kick taker's perspective and you can move the GamePad around to see where your players are positioned." This will let you not only aim the ball, but kick it with a curve as well.
The Wii U version of FIFA 13 will be ready... presumably some time after the Wii U hits the market.