I've been wondering if it could be made possible to transfer pokemon from older regions before obtaining all 8 badges. Not necessarily the high leveled ones, mind you, but those that are lower levels, perhaps between 5-10, also varying on how many gym badges you have obtained, similarly to the requirement of badges when it comes to the obedience of traded pokemon. I think it could encourage players to use some of the pokemon they captured but at the moment were too underleveled to fit in with the rest of the team, it could fit very well with starting the theme of starting over in each region.