Whilst I've started on my own in this industry about a year ago and can't really give you a recipe for success (anybody that can. let me know ;)), I can give you my analysis of looking at myself playing, being an Old Seadog of a Gamer Who Has Seen it All.
- Which characters are fun to play?
I mean, if you were playing (or example) the "American war here female soldier" and it was all kick-kick-punch-kick, would it be any fun? Would it be any more fun to kick-kick-punch-kick with an "ancient Egyptian inspired scarecrow"?
Consider going from the bottom up: look at your character ideas and consider what kind of cool moves could fit each of them (and maybe some sort of unique mechanic for extra powerful moves).
Maybe have a mini story (even if cheesy, cheey is good) for who they are and why they're there kicking the shit out of each other. (There's a wonderful analysis out there - sorry, lost the link - of why No Man's Sky sucks as a game because it has no story to drive the player, as analysed by an English Literature major).
So look at them from the point of view of the player controlling the character and making it do its think and consider what kind of cool moves make sense for them, what kind of upsides and downsides can there reasonably be part of said character in playing terms and what would make people want to play one sometimes but a different ones some other times.
Then look at them in terms of playing pairs - i.e. is there a character which would be so overpowering as being always dominant or there's always some kind of challenge on both sides for any fighting pair.
Coming from that angle you'll probably trim down your choices naturally AND end up with a cool story that might even inform you on the graphical design of characters and scenery.
PS: Just a suggestion. I might have no idea what I'm talking about. Take it with a pinch.