Pony Fantasy VI Remake

If I do need to do bug testing, then, what is needed?

You need a debugger. bsnes+ or snes9x debugger can do the job. First I'd set an execute breakpoint at C2/0B18 then step into/over until you reach C2/0B35. You should first check than the instructions are the same as the C2 disassembly except the change of the morph timer being on $1E35. If everything match then you gotta look more in depth if $1E35 is actually decremented and if all instance of it have been replaced and other changed morph code works properly (see asm file of Gogo's magic hack).