Starters are trainers first Pokemo

Smart people box anything past gen 4, it's why you don't see common NPCs with starter mons past then.

>>27940920
That's a good question. I like to think that they either come from a different region or are lab/artificially made.

>>27940920
They're rare, you only get them because the professor thinks you're better off with one of them then an early route shitmon. Pokedexes aren't cheap

>>27940920
I was always under the assumption that your starter pokemon could literally be any pokemon, but the story always has it coincidentally be a trio of grass, fire, and water to choose from. That's why in yellow you get a pikachu and your rival gets an eevee.