I find these quite interesting, I just recently got them from someone who tried to scam me. Great guy, you'd all like him. So I tried to "Restore" a hacked save to it (Pokemon Sapphire) using GBA Backup Tool. I dumped the save, and tried replacing the save with another. Yet strangely, it loaded the same save. It had me puzzled, so I looked into it and found that the save file is written to the rom it's self. I can confirm this because when loading the dumped rom in VBA, it loads my save file regardless of there being a .sav anywhere. Does anyone else here happen to know of a way to overwrite the ROM or save?