The only shiny Pokemon I've ever come across before X/Y were generated by the RNG manipulation method, which is still legal but requires some mathematics and fiddling. It wasn't until I got Y that I came across a completely random shiny Absol (one of my top 5 favorite Pokemon ever) when hatching them trying to get one with Super Luck, 3 eggs in. I got some Super Luck indeed!! Since then I've found about 5 more shiny Pokemon in Y. It's really thrilling.