Suki johnson

I loved this movie when I came out and I'm rewatching it today and some things don't make since. Why didn't they just use bunnelbe for the ground type? Why was Rayquaza shiny? All the other times we've seen Rayquaza it wasn't shiny? So why is it shiny now? Was it the sake for merch? If so just explain it. Plus how did latous latas and Rayquaza mega evolve with out a mega stone or key stone? If disproves all information we know about mega evolution in the shows and games. What is shadow hoopa? Can someone explain it to me?