I actually think Eragon-style timing would be perfect. Everything is really low tech and such, with everything being made of wood with thatched roofs most of the time, and farming being the main way of life. It's far enough in the past that ancient Pokemon are still alive but at the same time it's not so far back that everyone is dragging around a club saying "Ughn ugg."
Eggs, I think, are retarded for people not to have discovered. But I prefer to stay true to oviparous and viviparous, like animals. Mammalian Pokemon have live babies, reptilian and avian Pokemon have eggs, the like. The only reason they made all Pokemon lay eggs is to stay away from "where do babies come from?" So babies will come from the most reasonable place here.
I'm thinking maybe Pokemon are so heavily misunderstood, people have to use what they and their families have learned themselves. This also leaves room for misconceptions, which is good. Maybe that "all canine Pokemon are bad" in some families, and "blue Pokemon are all poisonous" in others. Ya know, kinda like how some people think all snakes are venomous.
That would make it fun, because you can't just push a button on a Pokedex and know what's up, or just rifle through a book. You have to ask someone who knows, or know yourself.
What kinda history were you going to freak on me?