I added the recipe for the Orechid and Orechid Ignem, and then turned to Astral Sorcery and gated the majority of the mod behind exploring biomes in the nether and, to a slight extent, the end.

However, when it came time to add Pixelmon ores to the Orcehid, I realized that I could not find a similar way to add them to Astral Sorcery. This might imply that I can't exercise fine-tuned control over Astral Sorcery's Mineralis ritual, and, if that's the case, I need to figure out what ores it does spawn (all ores? only vanilla ores? only a small hardcoded selection of moded ores?) so that I can get (or de-gate) it accordingly.

I have discovered how astral sorcery handles the Mineralis ritual. In it's server config file (the file created when the world is created; we can influence it through 'default configs'), there is the following options:

#Features generating random ores in AstralSorcery will not spawn ores from mods listed here.
	modidOreBlacklist = ["techreborn", "gregtech"]

This doesn't give me the ability to weight ore. It's possible it's weighted similarly to how the ore generates in the overworld normally, but its also possible it just randomly picks ores. I'm not going to touch it for now, and I'm going to close this issue; if it ends up being a problem, I will reopen the issue.