I hope it will take in place three things: environment(lake, river, etc), region(different parts of the world), and rarity.
Basically it would take your general region to make a massive list, then take different environments like lakes, forests, graveyards, etc. Of course some are rarer, being found in specific places listed(Great Lakes, etc) while some are extremely rare taking lots of luck to find and others are in extremely few locations. Then for legendaries, I want them to be LEGENDARY! Like, you see someone with an entei and you better bow down right away. I want some to be event exclusive like the mewtwo, and maybe some that will began roaming occasionally or be in certain locations
Basically it would take your general region to make a massive list, then take different environments like lakes, forests, graveyards, etc. Of course some are rarer, being found in specific places listed(Great Lakes, etc) while some are extremely rare taking lots of luck to find and others are in extremely few locations. Then for legendaries, I want them to be LEGENDARY! Like, you see someone with an entei and you better bow down right away. I want some to be event exclusive like the mewtwo, and maybe some that will began roaming occasionally or be in certain locations