Some questions

Could that same 'check for the last music' principle be used in this way: if the boss was just played, then I do get the fanfare and victory pose; if it wasn't, then no fanfare, no victory pose either. What do you think?

The following is doing this, skipping fanfare for every battle except the ones using the boss song (default one). Let's just hope $1301 retain the previous song value.

Code:

hirom
;header

org $C1011D
LDA $1301
CMP #$14
BNE exit
JSR sbrA

org $C1016A
exit:

org $C1FFE5
sbrA:
JSR $0105  
JSR $C10197    
LDA $2F49  
RTS