You know, I don’t think I’ve ever actually heard it quite that way around. I feel like the games and anime, when they leave hints about that kind of thing, are more likely to suggest that humans are from ‘Earth’ and Pokémon are the interlopers. Putting things this way around is, I suppose, one efficient way of explaining why there are humans in this world at all, but I actually don’t think it’s the only way, and I’m not sure I can think of any other questions that it simplifies, particularly.
I’ve never really given Elgyem and Beheeyem the attention they deserve, but my thinking on Clefairy has always been that there’s actually an interesting possible alternative that gets overlooked. Clefairy are capable of space flight and they’re obsessed with extraterrestrial materials and celestial phenomena… exactly like some humans. That could mean they’re from space, or it could mean that they’re from Earth and interested in extraterrestrial exploration, just like humans are. Having said that, though, I think the explanation Game Freak and the anime’s writers are probably trying to point us to is more likely that life on Pokémon Earth resulted from some form of panspermia-type event – a ‘seeding’ by organisms capable of surviving in space (rather than, say, some kind of bizarre Noah’s Ark scenario), implying that there may be other planets where descendants of the same species continued to evolve independently. In the real world, people who favour this hypothesis will point to bacteria and other resilient microorganisms that might lie dormant on asteroids for millions of years at a time, but in Pokémon we actually have complex organisms who can survive in space for extended periods – namely, Lunatone and Solrock. If that happened, though, it happened so long ago that it really no longer makes sense to consider Pokémon ‘alien’ – we’re most likely talking hundreds of millions of years for something like Solrock to give rise to the myriad species that exist today. Humans might be descended from those first Pokémon, or they might be descended from microorganisms that were there already – it’s sort of hard to say why it even matters. All of this… hrmm… conveniently fits with some of my wild speculation about mineral-form Rock-types being the ancestral state of all Pokémon (damnit, I hate finding evidence that I might have been right about Pokémon evolving from rocks), but then on the other hand, if I’m right about Carbink, they might even have been around since the damn planet formed in the first place.
One of these days I really need to try drinking heavily before attempting to deal with $#!t like this. It might make more sense that way.
Pokémaniacal 