Also they brought Rassilon back in the 'End of Time'
It wasn't clear from The 5 Doctors what his status was. He spoke to the Doctors, so probably timelocked or something similar.
Still, it took a lot of power to keep him that way until they needed him.
But, he regenerated from Richard Matthews into Timothy Dalton at some point. Did he still have his own regenerations or did the Timelords do that?