So, I finally learned how to insert sprites, find free space, re-issue image/palette pointers via a hex editor (still need to get the hang of hex editing, but I'm getting there), and such, all fine and dandy. But even after inserting a sprite to replace another, repointing it, and such...the image doesn't even change.
Am I missing something? I'm using firered as a base, and I even tried a clean rom.
Edit: If it helps, I can show you step by step of what I did with images.