Since the IV Generation, players have been able to preform a one-way Pokemon transfer to the current system, I'm sure this has been used by some of you here. And questions are interesting, so why not?
I prefer keeping my team in the game I raised them in, but I do use transferring for minor Pokedex completion. In IV Gen, I used the transfer feature to get the backdrops from each game and obtain a Snorlax and Kecleon for two Poketch apps. In V Gen, I transferred both my Celebi and shiny Entei, along with some random Pokemon, for the Zorua and Zoroark events. So other than that, I haven't used it all that much.
I prefer keeping my team in the game I raised them in, but I do use transferring for minor Pokedex completion. In IV Gen, I used the transfer feature to get the backdrops from each game and obtain a Snorlax and Kecleon for two Poketch apps. In V Gen, I transferred both my Celebi and shiny Entei, along with some random Pokemon, for the Zorua and Zoroark events. So other than that, I haven't used it all that much.