Here's my statement about Castform:
Wichu's Sprite Editor does not load Castform's alternate palettes, therefore it is impossible to edit Castform's backsprites with it. The only way is by using unLZ and then find the correct palette.
Second of all, Castform's front sprites in Gen IV and V are EXACTLY the same as in Gen III. I even checked. The backsprites however, are indeed different.
And lastly, I'm done. Yeah, I didn't do Castform back sprites. But I'm done. I'm just, done. There was truth to my statement of "I will no longer be working on this project".