Just look up RNG abuse Gen 5. You have to download a program. It is a bit difficult to master, but once you do you'll be getting shiny Rayquaza (if there is an event) and shiny Metagrosses with flawless IVs.
Don't even try it. It's still extremely difficult to find a shiny. If you really want good pokemon, try out this thing called RNG abuse. That's how my Mew is faster than your Infernape. It makes it easy to find shinies.