I don't actually stick to a certain rule. If I'm in a certain area, I'll put in some Pokémon from that area. One instance is putting in a Skiddo in Route 5. However, if I get a lame Pokémon from an English country, I'll pass it on to someone else.
3DS FC: 2707-2741-9594 Be warned, I may jump to epic fails of conclusions and general other errors. In advance, I apologise.