We don't know. Most of the parallel universes we've seen, such as Pete's World and the "Inferno" parallel universe, we've only seen small parts of them, and generally have seen no Time Lords other than the Doctor himself in them. That means that we have no idea where the Time Lords are in these parallel universes, if they exist at all. That said, if the Doctor exists in them (as the novels "Timewyrm: Revelation" (Virgin New Adventures novel) and "The Face of the Enemy" (BBC Past Doctor Adventures novel) confirmed the guy on the Unity is Strength poster from Inferno was an evil parallel Doctor) that means others probably exist tzoo. They weren't seen in "Rise of the Cybermen" though.