Kingdom Hearts II need help changing all of the shadow heartless into roxas (shadow doppelganger)

I have tried to change all of the shadow heartless and whenever I load the game up it does not load in the worlds I am in or will only show the the area with and the sky box but I cannot move around, open the in game menu. I had also tried starting a new game but that does not seem to work either. does someone have the codes to change the shadows to shadow roxas, if so, may I please have access to it? it would hep me with the problem I am having.