Is it possible to have a character have a custom boss them when the character is fighting a boss like eggman?

[juney]

So I'm working on a character mod and I was wondering if there was a way to make a lua script where the boss theme can be changed for the custom character that you are playing as without have it effect all characters. (Basically keeping the vanilla boss theme for the vanilla characters) Is it possible to make a custom boss theme for the character that the playing as without making the vanilla boss theme be replaced?

 

[amperbee]

It is possible, yeah.
You can try using a MusicChange hook to intercept a music change and override it with your own, or you can constantly override the current music to a different one whenever the local player is playing as your character with any other hook, like ThinkFrame.

(Disclaimer: I have not tried the former method, but I'm pretty sure it'd work. It's the cleanest solution available.
The latter is a sure way to get it working, but it is overkill and may make things not work correctly if a mod wants to mess with music too.)