If thats how its gonna be for the artists, I'll take Ninja and Sword for now (I don't want to take all the good ones now)  . 
Now that I think about it... depending on the amount of artists we get, I think we should have each artist do 2-3 abilities and a boss and/or planet.  I'll probably pick my last ability after some other artists have chosen theirs, and I've already illustrated the Computer Virus Boss. 
So far we have: 
KWarp:  Abilities: Yoyo, Plasma, Cutter.  Bosses/Planets:  ---. 
CarefreeCaptain:  Abilities:  Sword, Ninja.  Bosses/Planets:  Computer Virus. 
Oltri:  Abilities:  Mirror, Fighter.  Bosses/Planets: ---.