>>24542211>500 Pokemon>3 REGIONS each with 8 GYMS>>24542228>A region UNDERWATER and one above CLOUDSYou have some ambitious thing right there and I can respect your imagination, it certainly looks cute. But I really doubt that you will create something like that, do you know how program? This could work in a Rpg Maker, but it still is too much content.
I recommend to try things in a realistic way, I've seen many people along the years trying to do something too ambitious just to fail near of the start.