Look at all the screenshots. Notice how some of the Pikmin have flowers on their head and others don't?
(http://img.photobucket.com/albums/v641/Mariorocks/Pikmin2.jpg)(http://img.photobucket.com/albums/v641/Mariorocks/Pikmin.jpg)
In the Pikmin games, they had to eat nectar to grow a flower on their heads. When the flower sprouted, they got much stronger. It will be interesting to see how this works.
Also in the first screenshot Captain Olimar is holding on to the yellow Pikmin. Since the yellow Pikmin had to ability to jump high maybe it's Captain Olimar's Up+B move?
Good find!
Yeah maybe they grow later on in battle, so then Olimar gets much stronger during a battle...