Nintendo has confirmed that you can only use voice chat for some of the games in Wii U. Finally Nintendo Put an end to this big rumor that Wii U have Voice Chat feature during Game by default. But the final result is here today.
The voice chat during games is not enabled by default on Wii U, which is finally confirmed by Nintendo. Voice Chat option may only be used with three games: Assassin’s Creed 3, Mass Effect 3 and Call of Duty: Black Ops 2. If you want to use voice chat during game then you have to use a headset with microphone connected, which is compatible to Wii U gamepad.
Instead of using the microphone players will have to connect to the headphones compatible to Wii U gamepad for gameplay ie marks or Mad Catz Turtle Beach. Nintendo has not indicated that it intends to support a headset wirelessly, so for now, play with voice chat for now Wii U will be limited to three games and with certain headphones.