Trooper

I found this hack the other day and have been playing it all weekend. Really like it. But I was wondering. How come it seems like some Pokemon are just randomly shiny? Like Magnezone and Kangaskhan are the ones I've seen so far. Team Charm, Grovyle, Volbeat, and Illumise also appear shiny in the game's intro video before the titlescreen. I'm not complaining or anything, but I'm wondering why the change was made.