Sonic: Lost World producer Takashi Iizuka has confirmed that the game will only have local multiplayer on Wii U, but online on the 3DS.
In an interview with Nintendo World Report, Iizuka confirmed that the Wii U and 3DS version will have different multiplayer modes.
"On the Wii U, there's booth cooperative and versus multiplayer," he says. "In cooperative play, Sonic will be using the Wii U GamePad and someone can be supporting Sonic in co-op with the Wii Remote. In versus mode, one player will be playing on the TV screen and the other player will be racing using the GamePad so you don't have to have split screen."
The Wii U's multiplayer will not be online, pushing for an "on the couch", shared experience. The 3DS version however, will be online supporting "4-player versus racing over Wi-Fi and the Internet."
Multiplayer is not the only aspect that will differ between the two versions. According to Iizuka, while the story and general theme of the levels and game will be the same in both versions, the level design will be completely different. "There's not a single level in the Wii U and the 3DS that overlap and appear in both games," he says.
Sonic: Lost World is the first Sonic title in a three-game deal to come from a partnership with Nintendo and Sega. You can see the game in action in this 12-minute gameplay video.

http://www.computerandvideogames.com...ayer-detailed/