I do use Showdown, but I don't go on the PC server a lot. I go on the main server mainly because I like to battle in a lot of tiers that not a lot of people play such as BW NU, CAP, and Monotype. If you're wondering what username I go by, I'm always Slayr231 wherever I go.
Which brings the question, do you use the same username for all sites, or make up different ones for each site?