so with gen 6 it's made pretty clear that there is an RPG theme within the starter trio as they embodify the tank, mage, and thief roles.
The gen 2 starters embodify being pure beings of their element in a sort of plainness, and I think I recall reading somewhere that Samirott is Japan, Emboar is China and Serperior is France?
Gen 4 has the monkey king, Napoleon, and what I think is that turtle that grew the world on its back in that one story but I have no idea how they relate if at all.
Gens 1 and 3 I just don't know