Looks like Sonic & All-Stars Racing Transformed isn't going to be equal on all platforms. Executive producer Steve Lycett revealed recently that the Wii U version will not support voice chat.
News of this popped up on the game's official forums, when a user linked to news regarding the Wii U's online chat capabilities -- or lack thereof. Voice chat will vary per game, and as of now, only Assassin's Creed 3, Mass Effect 3: Wii U Edition and Black Ops 2 will both support this feature. However, players looking to communicate in multiplayer will need to use a third-party headset, as games cannot use the GamePad's native mic.
The Wii U Pro Controller also doesn't have a headphone jack, so you're going to have to plug your headset into the GamePad even if you're sticking with controller.
In regards to Sonic & All-Stars Racing Transformed, Lycett notes that for those reasons, the Wii U version simply doesn't have voice chat.
"We don't support voice chat on WiiU for those reasons, one of the side effects of being a launch title basically. Does support it on PS3 and 360 though!"
Good to know other versions are fine, at least. Expect the game to land on November 20.