A collection of the FBA controller configs I use in RetroPie for Capcom and SNK fighting games.

The most useful part to get from this is simply understanding how FBA maps A, B, X, Y, L, & R to the original arcade buttons. Here's what that looks like for Capcom and SNK fighting games:

A_=LP
Y_=LK
X_=MP
L_=MK
B_=HP
R_=HK

A_=Arcade-A
X_=Arcade-B
B_=Arcade-C
Y_=Arcade-D

While I have my controls set up with LK & LP on the shoulder buttons, you can customize the configuration however you would like.