Hi all. I decided to compile this list of Pokemon rarity classifications based off Admin Red's rarity spawn dump. It's basically just all catchable land/water spawn Pokemon listed alongside their most common spawn tier, so as to ensure easier Ctrl + F searching. :)
There are 10 total rarity tiers (though only the first 9 are used in this guide):
ABUNDANT
COMMON
UNCOMMON
MEAGRE
OCCASIONAL
SCARCE
SPARSE
RARE
EXTREMELY RARE
LIMITED
From what I understand, there seem to be certain maps where a Pokemon is more likely to spawn, as Red's post shows some Pokemon having various rarity tiers listed (e.g. #11 Metapod has lines with both "Common" and "Uncommon," implying its spawn rate differs depending on the map). However, this will require further testing, since I'm not sure which lines of rarity correspond to which maps the Pokemon appears on.
Asterisks next to the Pokemon's name indicate that it's listed under multiple rarity tiers on Red's post. If there are multiple rarity tiers listed for one Pokemon, I'll defer to the lowest/least rare spawn tier it's listed under. If you see an asterisk next to the Pokemon you're searching for, you should still cross-reference it with Red's post, though - there are some Pokemon listed as "scarce* " that may also be "extremely rare" on other maps, for example.
Land spawn Pokemon:</U><i></i>
<U>Water spawn Pokemon: