I stopped at Gen 3, because a DS was just getting too expensive to justify, and getting 2 to trade between games was out of the question at the time. As it was, the screen broke on my second GBA, and I had to set trades up on my working one and then do them based on sound and matching key movements. It was...an interesting time, to be sure.
Got into Pokemon GO just to catch up on all the Pokémon I missed out on.