How about this...
Its kind of like Isle Delfino, but not.
When the battle starts out you are in the landing site from the first Pikmin. As time passes it get later in the day, and when night time comes, several onions take off and fly into the sky. During this night time perioid, you must use the onions as platforms. Eventually day will come again, and you will land in a new level. Every level starts out calm but eventually creatures like Bulborbs and Snagrets attack players. The closer it is to night, the more vicious the critters will be.
It sounds fun to me, and the changing levels idea would match the song on the Dojo nicely.
I like obsessing over Pikmin :P