I'm too lazy to actually go find the thread that we were talking about this in, but it would most likely involve requiring the gym badges from that region for pokemon of certain levels to obey you.I love the idea of all pokemon being obtainable, and all the regions being implemented. But after the second region most of your pokemon would be close to level 100. So there would need to be a system where you leave your pokemon behind and start fresh or something.Don't forget the possibility of having all the regions implemented so it is actually possible to catch almost every single Pokemon.(starters would still have to be traded in to complete the Pokedex, but the point is that all Pokemon would be able to be caught legitimately.
Of course, you could also make it where the player can't bring in their Pokemon from another region until they've gotten all the badges from that region.
