I know that from what I've heard, making any type of fighting is difficult and it's one of the hardest genres to develop for but from any one with either experience or knowledge. Which do you think is harder to make?

i'm not basing this off any factual knowledge so don't quote me on this, but part of me wants to say fighting games like Smash Bros. are trickier to make because the characters have more movement compared to a standard fighter like Street Fighter, where the two characters face off against each other and usually only move back and forth. 

again, no factual knowledge here so i could be wrong, in which case someone will surely come along and correct me. 

Both are just as hard to make although for different reasons for each and it all depends on how the mechanic of said fighting game work

 

Even in regular fighting games they're vastly different,Tekken is Different from Street Fighter which is different from Persona 4 Arena which is different from Marvel Vs Capcom..........etc