I'm not a fan of shoehorning IP in for the sake of it... But I don't think this would be a bad thing necessarily. IASW could use a little excitement. Provided that the characters match the theme, country, etc. Throwing Baymax or Vampirina in there would not work. Of course, that also means that only a few characters actually meet the criteria. Sure, Olaf fits in with say, Norway. Or Mufasa in Africa. But where would you put Mickey? Stick with the few that actually work, and make them as "hidden characters" to discover. That is, don't go overboard.