>>20530680IV's are passed down. 5 random IV's between parents if one is holding a Destiny Knot I believe.
Basically,the maxemise the best chance at getting High IV shiny offspring, get two 6IV parents and make sure one is holding a Destiny Knot.
I probably explained that terribly, but luckily for you, i have this picture. DONT get put off by how much information there is, its really easy once you wrap your head around it.