Where to find rules and ban lists for OU?

I was just in a match on Pokemon Showdown with a speed boost Scolipede. The team builder didn't stop me, but my opponent said that it was on the ban list. So I try to find out if this is true, and I can't find anything that says it is, but I do see that having drizzle and swift swim on the same team is apparently banned. Where can I find the actual rules and bans for OU?