Imagine a final pokemon game where you go through each of the regions, and at the end of each region you leave your pokemon with the professor and move on to the next area. once you reach the end of the game and face the final elite four you can choose a team from your entire collection to fight. the elite 4 (could be more than 4 i guess since there are more than 4 regions) consists of the champion of each region and the final battle is against red