It seems like all I do now days is answer posts asking for more details... but I do think more would be helpful here.
I want to include a variety of classes
This isn't clear what classes are? I'm guessing an RPG type class like Wizard, or Warrior, etc...
hot-seat multiplayer game
Will everybody use the exact same controls?
code all the skills and abilities for every class FOUR times for each player
Why not have only one character sprite, but multiple instances of him for each player. That way the core abilities will apply to the sprite and only those things unique per player will change.
But I'm not the best to answer this on the whole as I have not made a hot-seat multiplayer game yet. I though Souljaboy was?