Ok, to do this correctly, you need to have the save file FireRed(X).GBA/, If you dont have the file all you have to do is copy the origional FireRed.GBA/ file and rename it exactly this FireRed(X).GBA. Ok you must not have fought HO-OH to do this also. when you start up with with FireRed(X), go to the area where HO-OH is located (you still need the Rainbow Wing) once you've made your way through the maze, you will encounter HO-OH (NOTE) He will be stronger due to FireRed(X). you must catch him at all costs. I suggest that you use Ultra Balls instead of wasting your Master Ball on him. Once you've caught him, check his item that he is holding. Instead of the usual Sacred Ash that he carries, you will instead have a Master Ball waiting for you.

Enjoy Arcane