DraStic

When I go onto the cheat list for my pokemon heart gold, the page is empty with no option to add codes. I''ve tried to find a solution but it looks like everyone's roms come with cheats on default

Drastic checks various things for understand who is the game are you playing for give the right set of cheats.
If it is a ROM hack, Drastic sometimes thinks that it is another game.
Try another rom.

Also, you can add cheats manually with Custom Cheats