[ASM & Hex] Changing Marowak Ghost in FireRed

Hey I've tried looking up how to change Marowak to a different Pokemon in FireRed to little avail. I know changing the battle scripts in XSE does not work and this runs off of a special so it must be in the hex somewhere.

Does anyone know what bytes this data is at? And how I would go about changing Marowak to something else

thanks to chaos rush (2013),
routine is at 0807f904
level is at 0807f938

just look somewhere in there for it, it's likely there ehehe <3