Wii Party will be huge! Surprise!
I honestly believe Kirby could be a big surprise if marketed well. It's a 2D platformer with an amazing art style and really interesting gameplay, and it has co-op(I think). If it manages to become a 10m plus seller I wouldn't be surprised!
System sellers...hm...Metroid and Donkey Kong!
So, Kirby will sell 10m, and Metroid and DKCR will move consoles. Wii Party is just to obvious, FlingSmash will not be a huge seller; PokéPark will underperform.