You know how they have that checklist on planes when you go to Hawaii or other such exotic places. To check if you're bringing in any outside bugs, plants, and animals? Yeah they don't do that in the Pokemon world.
Either that, or the crazy Unown theory is true. There are no variety of pokemon. They are all Unown. When a bunch of Unown gather together, they spell a pokemon's name and then evolve into an egg of that pokemon. That's why we don't see the breeding process of Pokemon. Pokemon don't breed. Those daycare center couple were telling the truth when they have no idea where that egg came from. A bunch of Unown sneaked in, saw your pokemon, then spelled out its name, and bam. You have the egg. No inferred ***** happening.
The reason why the new pokemon are appearing in old regions is because the Unown are getting smarter. They can spell more words now. And just wait until the day the Unown get even smarter than they are now. Their takeover is drawing near.
Well they did create all of those Pokemon in the third movie. Also what happens when they spell there own name?
This is why Deoxys is uber: http://i.imgur.com/qHEQt This is a picture of some cute kittens: http://i.imgur.com/wfdOk