When you make a trade with someone from a different region through the GTS or over WiFi, the region will appear on the list. As there are 130 Different Locations, they take up each floor. The game will keep track of how many people you have traded with and will let you interact with these characters. The characters remember what you traded, when you traded and how many people the person itself has traded with. They tend to make a comment about the region and the various Pokémon they have traded.
Pretty Much You will see every Pokemon you traded from a Different region
They tend to make a comment about the region and the various Pokémon they have traded. This is the most Information I Have Found At This Source