Welcome to Gaia! ::

1) hack
2) trade
3) breed a Japanese pokemon and a American
4) pray to your god

Walkthrough 101:
Go to iron island and help this riley dude out. But save before you get egg. if you hatch it and it's female your lucky, cause now you'll have a 500-1 chance of getting it. But if you keep restarting to save before getting it, the egg from riley has a 100-1 chance of being shiny. and yes any other way is 1000-1 chance getting it. last lastly if you get a male shiny lurio you can breed it with ONLY FEMALE LUCARIO to get a 50-1 chance of getting shiny smile . i hope this helps cause it helped me a lot when trying this, i now have 8 shiny lucarios (no i will not trade them cause my house has no online hotsport sry sad )