Okay, then we could say that Hammer's resources turn Vanko into a credible threat if you'd prefer to formulate it that way.He doesn't turn Justin Hammer into a credible threat. While he ostensibly builds the weaponry in Hammer's facility, Hammer is never in control. Vanko immediately & effortlessly seizes control when it suits his purposes.
So he goes from being a bum in a Russian basement to nearly defeating both Iron Man and Rhodey in the middle of Stark Expo. Say what you will about the film's quality, I'd hardly call that a story arc that "really doesn't go anyway in the film."And while he did set the finale of the film in motion, I don't think it was a particularly impressive finale.![]()
Like I said, I never really felt the jeopardy in the finale. At no time did I think, "Oh crap! Tony & Rhodey are so screwed!" I think Motion Picture Comics put it best:

http://motionpicturescomics.com/category/comic-post/?tag=iron-man-2