Question: why is galadriel more powerful than gandalf?
Answer: Galadriel was never more powerful than Gandalf! ... Gandalf appeared to be weaker than Galadriel, because he was trapped in a human form and the Valar had placed limitations to the extent of power he could have used. If at all Gandalf had used all his might to deal with Sauron, there would be no Middle-earth left.