I've been playing the main Pok?mon games since getting Yellow for Christmas 1999, but I've had several off-periods where I didn't play as much or at all. I'll break the timeline down as follows:
1999-c. 2003: Played Yellow, then Blue, and the three Generation II entries on nearly a daily basis.
2003-late 2005: My playing of the Pok?mon games dropped off considerably during this time, and I never got a Game Boy Advance to play Generation III, which I was kind of turned off from due to the fact that you couldn't import Pok?mon from the early two generations into the Advance Generation games.
2006-2012: I traded in all my Pok?mon games that I had at the time in early 2006, as I tried to get out of the franchise entirely.
c. mid-2012-2015: As I was starting to go through some rough times in my life, I started playing the Generation I and II games that I grew up with via emulators, and towards the end of this period (around mid-2014), I began having thoughts of looking for used copies of the Game Boy main series games that I once owned, and a job coach that I worked with around that time told me about the Generation VI games, particularly the Hoenn remakes.
January 2015-present: After being talked into it by the aforementioned job coach, I bought myself a used 2DS and a used copy of Alpha Sapphire, as I wanted to get back in by doing the then-current generation. Although I played Alpha Sapphire quite a bit in the first few months, like previous periods, my activity dropped off since, and I don't play the games very much now. However, I've since added Y, the three Generation I Virtual Console re-releases, and Moon. Thought I hardly play Y or Moon at all (and am less than impressed with most of the changes brought about in Sun/Moon), I do play the VC Red, Blue, and Yellow every once in awhile.