I was stuck on that one too, somehow I passed it after switching my pikmins around a bit until I had the same colors as the ones in the event's pic, aka one white, one purple, one yellow, one blue and two reds. Dunno if the order is important tho!
I am yet to play it, but reading other's posts, all you have to do is survive until all your pikmin grow flowers. Hope that helps.
I think you need a certain amount with flowers, I had two or three Pikmin with flowers following me and it didn't work, so I tried getting the max amount of Pikmin and it worked once they had flowers.
Objective is to have 6 pikmins with flowers on their heads. You start with 3 pikmin, hit B on the GC controller (don't know about Wiimote), till you have 6. Then survive untill they all have flowers. It sure helps to be able to read Japanese :-)
