I've had a time with my hack, in my hack i had it where crono was supposed to fight the second form of lavos, but everytime it would cause a glitch. The music on the 1000 AD map would change at all, even from locations like The mellinum fair or Guradia forest. If you stayed on the world map long enough the game will stop playing music and it will freeze, if you're moving around the time the music stop, you can still move around, but trying to go into the buildings, menu's and wide view of the map will cause the game to freeze, so if you have any scene involving lavos. (i don't know if the the same thing happens on all the forms.) just make sure to store something into unused memory and have it call up in the lavos core section, then create a new scene in there. This will make sure that your game won't bug out.
for example
for my intro i have this in my event code.
Bitmath(mem.7f0234, 01 set)
assign(mem.7f0234, mem.7e25f6, one)
now in the lavos core event i have this setup in the lavos object code, if you put this in object 00 the game will freeze.
assign(mem.7e25f6, mem.7f0234, one)
if(mem.7f0234 == 01)
- Textbox(bottom, "{Crono} Test.{null}"
- Changelocation(loc 1eb, x10, y10, 40)
That makes it where you don't fight second lavos fight only if you have 7F25F6 = 01 if it's 00 or 02 and above you will fight him.
You can try this method or another method of your own.