Well, considering that Sasuke forced Danzo to use a last resort justu that would end his life, I would say that Sasuke won the fight. Izanagi and MS are both just techniques, you can argue the whole "he would be dead if not for ____" either way. As for Obito and Karin...they weren't that helpful and even if they were, since when does getting info about your enemy from a friend disqualify you? At the beginning its true that Danzo was holding back so he could fight Obito, but once the fight began to get serious, he was forced to take Sasuke more seriously. He ended up using all of his izanagi, if you're still doubtful that Danzo was fighting Sasuke full force. And also as others have been saying, if someone started shooting out black liquid, you wouldn't need someone to tell you to clear the area.