In regards the Goro's suit; the costume was not just two guys standing on top of each other. The top half was a very intricate 120 pound puppet. The top arms were also not linked to the suit performers arms, but controlled remotely by a separate puppeteer using telemetry controls where the puppet would mimic their movements.
http://www.youtube.com/watch?v=vVi2klX_feE
http://www.comicbookmovie.com/fansites/nailbiter111/news/?a=69710