From the mouth of Kirby:
Sudden Death Mode is up on the downloadable version.
-There are a few bugs with it, sometimes it ends the game early
-With this mode, comes being defeated. Once tagged you are out for the remainder of the game as a boo. But soon you might be able to shake stuff to help the IT player.
There are now 31 Total characters, not including mine and Mario's.
If you have any suggestions on more then post under suggestions on the forum.