universal-pokemon-randomizer VS PokeExpansion

You might also want to use Brentspector's fork, or some experimental branch of ZX, if you are looking for specific features. Though the former is slowly falling more behind as afaik Brentspector has stopped working on it, and experimental branches can be buggy and have to be built before using.

This version of the UPR works with FireRed Randomizable 809.

Randomizers generally don't like ROM hacks, unless they are built-in of course like with Unbound. The Universal Pokémon Randomizer (UPR) relies on manually entered offsets for ROMs, like where tables for all the data are found. (for examples, look in the .ini files here) It is possible to enter these offsets for ROM hacks too, but afaik it has only ever been done to Gaia, Randomizable 809, and a few Speedchoice ROMs.

There is, in Brentspector’s branch.

Brentspector’s branch of the UPR should work with FireRed 809 Randomizable (not to be confused with 898 Randomizer!).

Gaia can be randomized with its own customized randomizer, and FireRed Randomizable 809 can be as well, with the best support in Brentspector’s branch of the UPR.

Here is link number 1 - Previous text "UPR"

If you have a ROM hack you want supported (and it's Gen 3), then yes. This will also enable adding in support for Static pokemon. There is no full list of possible overrides, but most can be found between the Fire Red 1.1 (U) in gen3_offsets.ini and the gen3_hack_offsets.ini file. Let me know if you want more details. I'd love to expand support for more hacks.

for instance you said "i'm already using that" but i think that's unlikely. is it possible you're using dizzyeggg's pokeexpansion? what i linked is rhh's pokeemerald-expansion. they are similarly named but not related at all. you shouldn't use PGE with rhh's expansion, and i don't think python is involved in the setup at all.

Sapphire is generally not used as ROM base. If you decide to use Emerald, you can use this instead: https://github.com/DizzyEggg/PokeExpansion.