When I asked the question: How to get reggigigas, One of the answers said "you have to migrate from a movie" I really need help.
You don't. There was a Mystery Gift Regigigas from a movie a while back which enabled you to catch the three Regis. This enabled you to catch another Regigigas in Platinum.
there was a TRU event giving out a regigigas in honor of its new movie
but u do not get it from the movie itself