To my knowledge the so called
were the Valar. Gandalf an dthe other Istari were sent by the Valar to Middle Earth to help teh peoples of ME to realise their strength, and defeat Sauron themselves.
Gandalf talks at some point about facing Sauron one-on-one, but i can't remember any more. If Sauron had the One Ring, he would most likely beat Gandalf.