When they're on form, the Time Lords.
For starters they created the TARDIS, a virtually invulnerable ship that can travel through space and time, is bigger on the inside and is capable of hauling planets about (as much as I'd like to forget that ending).
And that's just the outdated "junk" the Doctor travels in.
They can teleport planets around time and space, trap them in eternal force fields or stick whole solar systems into a time loop at a flick of a switch.
According to the Doctor, there is at least one civilization that would undo either Time Lords or Daleks if even one of them went rogue: the Osirans. The Doctor trapped Sutekh, but had he lived nothing would have overcome him.