it can be done, but i think it would take 6 times as much work to pull it off on Openbor than in a 3D engine.
when it comes to Vs fighters
Smash brothers works because it is way too simplified, & the way 3D engines are programmed give you a chance to program collition reactions in a more "realtime" fashion, same with particle physics & such, so most characters will react in a generic way when hit (ragdoll physics routines) & that will "unify" the look. it depends on your game engine.
then after that , what's left for some of the weirder characters is personalized & scripted animations related to hits & such on themselves (MR game & watch - Wario)
you may want to go further & program enemy reactions based on what character is attacking them - example:
mr game & watch hits a foe & the foe reacts in weird 4 frame pain reactions, othewise if Ryu hits an enemy the enemy reacts at normal frame-rate & realistic physics.
ina 3D engine like Blender, you can choose what physics you enable & increase or decrease, so it stands to reason a more detailed engine can even give certain objects "cartoon" properties & realistic properties to others.
want to go even further?
game & watch hits an enemy - weird 8 bit frame style pain reaction & death animation
Ryu hits an enemy - normal realistic pain animation & slow down death (on the enemy only)
Mortal Kombat, KI or Night Slashers character hits an enemy - You see a pain animation with blood & gore, enemy dies in a bloody mess
in a 2D engine like OpenBOR or Mugen you pretty much have to do a reaction in a character by character basis, so its a ton of work.
Sure scripting might pull it off, but it will probably be so much script, that at the end of the day it would be like a whole new verison of OpenBor
another problem is the sprite size, in
O Ilusionista's Avengers module, speedsters work really well because of the smaller sprites, but in game with big sprites like Final Fight, making speedster characters (sonic) work is very unlikely.
again going back to smash bros, it took years for a AAA company to pull off a "simple" fighting game with resources in the millions if not billions (thousands of millions) & top notch programmers to make a "multiverse" game that feels good, so to make a beatthemup on the same level it will take double that...