Nintendo of Americas has stated that Pikmin 3 will be available during the launch window of the Wii U console. The game will be releasing before March 31st, 2013, the cutoff window for a launch release.
Pikmin 3 will be released for the Wii U in spring of 2013 in Japan, and sometime between the system release on November 18th, 2012 and March 31st, 2013.
So the Japan release will be sometime between March and June and the North American within four months of the system release. No news about when the European release of Pikmin 3 will be coming however.
Pikmin 3 is an upcoming real-time strategy game for the Wii U console. It is a sequel to the Nintendo GameCube game Pikmin 2 and the third game in the series. Pikmin 3 will expand on the gameplay of games in the series, with players taking control of up to 100 creatures known as Pikmin. Players will be able to play Pikmin 3 using the Wii U GamePad or the Wii Remote and Nunchuk.