In response to Djukor: The approximate chances of running into a shiny, female Riolu are about 0.00015%, without utilizing any of the methods for increasing the chances of running into/breeding a shiny pokemon.
The numbers behind this are as follow:
Gender of Riolu: Male (87.5%), Female (12.5%) Chance of Shiny Encounter: 1 in 8192 (approximately 0.012%)