The chance for getting a perfect pokemon Iv's is 1,073,741,824.
I wish.
I have never gotten a pokemon with imperfect Iv's since I got 2 shiny's back to back when I returned to my Pokemon Diamond blind run (Finished) save, which where a bronzong and a golbat. What does this mean? Well...
Every Starter
Every wild Encounter
Every Event Pokemon.
So ya... Kinda a big deal here.