ROMs, both modded and unmodded. For years, the most reliable way to get Fire Red (U) (Squirrels), which is one of the most used base Pokemon ROMs for modding is the Archive. Luckily it's still there with 1,574,966 views.

I don't see any ROMs and the ToS say no uploading modified or unmodified ROMS.

https://romhack.ing/help/rules