1,028 eggs for Shiny Vanillite (before Shiny Charm) in X. I actually hatched even more than that if you count the half a year I spent trying on Black Version to no avail.
Over 1,362 eggs and still didn't hatch a Shiny Tyrogue. Gave up and chained one in Platinum.
I hatched 3 Shiny females before it, but it took 1,125 eggs to get a Shiny male Burmy (after Shiny Charm, I think). Those females almost made me rage quit (since I was aiming for a Shiny Mothim).