best for a stylized 2D side-scrolling fighting game.
well it would have to be a society and technology level where they would fight hand to hand.
1800's or the wild west and you're in a gunfight, not kickboxing.
native americans had things like indian wrestling and counting coup.
conquistadors would use pistols and swords, Kahns would use swords, and australians would use swords or guns depending on the period.
so none of them really makes much sense, and would probably come off as just being plain silly - picture waytt earp vs ike clanton doing the mortal combat thing.
so what would make sense,and not just look silly? well, where did they actually do mortal combat type stuff? ancient asia of course. but they usually had swords and such too. that's why many fighting games are set in asia.
tough inner city hoods back before every kid over 5 carried a gun would work - but only for high school street punks. anyone serious would get a gun.
so appropriate settings are really rather limited.
when "based on the real world" isn't working, there's always totally fictional settings as a possibility.
Scratch that and change it the Communist Revolution of Russia in 1917.
doesn't help, they would still use guns. lenin vs trotsky in kickboxing? pleeze!
the problem boils down to king fu vs cowboy:. kung fu does a whirlwind kick, cowboy whips out his colt and drops kung fu in one shot. game over. so any setting with readily available firearms is pretty much out of the question. the same idea for swords: conquistador runs kung fu through, game over. now if you give kung fu a sword too... but then its not a fighting game anymore. its a fencing game.or give them guns and its a shootout game, like the old arcade game tombstone.
the one thing i would not do is choose a setting where it would be a kung fu vs cowboy situation in real life. which really only leaves two possible settings: ancient asia (without swords or other hand weapons), and fictional settings.