Doubles still uses the live queue for matchmaking, but isn't ranked yet - we're getting the ladder mechanic right on Singles first, then extending it to team formats.

New players start unranked and join the ladder after their first win. Beat someone ranked above you and you jump halfway to their rank. Beating someone below you changes nothing - there's no reward for farming weaker opponents. Losing doesn't move you down, unless you lose to the person directly below you, in which case they leapfrog you.