I'd say those 4 and whoever else you like playing. for deadpool, I'd recommend pushing him to the corner and heavy spamming with ghost. extremely easy, because he can't throw specials, and ghosts heavy is spaced so you can lock him there. I doubt you'll use the final person in your slot, because your other champs aren't very good and the others are higher level
Havok for Electro Boss only do mediums and SP3. Ghost for Deadpool X Force.