So I would like to thank Slith265 for the tip of using GraphicsGale, it's a good tool to recolor the most difficult parts.
but now I have a little problem, after putting the custom images in the folder of the game, the back of the pokemon gets a white background or black at the time of the fights, being against wild pokemon or common trainers, already tried to copy the background of other images and the error still persists.
so anyone here knows how to solve this?