How to Create the Pokémon HeartGold/SoulSilver Xenophobia Rom from a Good Dump
Once again, I have discovered an old (2012) romhack of Drayano's that requires a bad dump in order to patch it.
Once again, I will provide instructions on how to patch Sacred Gold and Storm Silver using a legitimate good dump of the game.
16 October 2023 edit: And once again, I am wrong! I wrote this post quickly and misremembered some things. I've actually only encountered one other hack of Drayano's that uses a bad dump as a base rom (which has since been fixed). I'm writing this addition because, I don't know why I didn't think to try this earlier, but Drayano's twitter bio has a Google Drive link to all of his old romhacks with fixed patches!
Of course, these instructions will help with any romhack that requires these bad dumps: decrypted CRC32 of FFD28F00 for HeartGold and EBB387E7 for SoulSilver.
Method 1: Hex Editing Instructions
Method 2: Patches
After you have modified the good dump using either method 1 or method 2, you can apply the Sacred Gold or Storm Silver patch, or whatever romhack patch requires these bad dump base roms.