["Three for three"? Should we ask what that's supposed to mean...]

Yes, I think so. There are plenty of things that have still been yet to be discovered about the past, I'm sure, but we do at least have some clue of what the world might have been like before humans came along, and what kind of Pokemon may have been around during that time. There were many Pokemon that used to live in ancient jungles, or even some that once lived in our oceans as well.