One problem. If he uses a demagnetized armor, which his newest model is, it forms a barrier around him that Magneto couldn't penetrate. Iron Man took that into consideration when he beat it. The fight between him and Magneto would be a battle of magnetism vs repulsor rays. However, if Iron Man gets close enough to Magneto and punches him, I don't think Magneto can withstand the hit. Iron man can lift about 80 pounds in his current armor. It would be a tough match, which is why I put it in there.