I kinda feel like I'm making a shameless plug, even though it's a crappy hack from long ago...
The More than 4 Sacred Weapons hack?
It's obvious someone can improve it with minimal effort.
That was like... my first ASM hack >_>;
0x00 = No BGM or Flash
0x01 = BGM and Flash
0x02 or anything else = Flash Only
An array of 255 items 0x01, 0x02, or 0x00 at 0xFFFC90.
...My gosh that's horrible. I don't even have the source anymore.