Party vs Party.. how hard would a multiplayer sprite game be?

I was thinking about FFI and how badass my party was, when I wondered how badass other people's parties were and if I could pull off a win.

I do know the characters do massive damage past how many HP they have, so maybe making attacks weaker by a level percentage would be for the best.

But what should the percentage be? And how hard do you think the game would be to make (as) freeware?

using a gameboy link cable i guess you could do party battles. i might be a good idea.