Number of forums I joined? Maybe around 50, and being Staff about 30-40 of them. XD
Well it's true, a long time ago back when I was still a member I used to join lots of small Pokemon forums and I made my own forums.
But the large ones were Pok?mon Community (duh XD), Bulbagarden, Serebii, Pok?mon Fan Universe, and Pok?School. I think that's it.
As time went on I moved away from all them other forums and now I only go to PC.