This is the one story line that would be great for including tons of villians in one single movie. There is no need to tell anything more then a villians name in this case (if that), you simply have Tony state he will go after ANYONE using his tech, and start showing lots of 'local' random small B-listers that he hunts down in the States and Canada (quick montage battles, use CGI on these guys to keep costs down), but eventually has to make it an international issue and goes after Titanium Man and Crimson Dynamo (which get explained in more depth).