A while back, I saw an interesting topic on the Pikmin 2 board, where each user posts something they think will be in Pikmin 3. Each person is allowed to post one thing per post, one post per day. It can be anything, from Onions to rainbow pikmin, almost certain or nearly impossible. It can be something shown in the the Pikmin 3 trailers or videos. And yes, it has to be something actually IN the game, so don't say the Wii U tablet or anything of the sort.
Once Pikmin 3 is released, each correct guess is worth a point. The person with the most points wins (provided this topic stays alive until Pikmin 3 is released).