What is the fastest way to level up my Pokemon in X & Y?

So far, the only ways I know of how to make Pokemon level up fast and furious are Victory Road, the Elite Four, and, probably the most effective, the Battle Chateau with the Black Writ of Challenge in effect (and yes, I have made it to Grand Duke before I wrote this), but are there other ways that I do not know of at the moment that are even better, or are my strategies the best the game has to offer? I just wanted to make sure so that I was doing it properly and that it serves me well for the future ahead.

Pleaselog inorregisterto add a comment.

OOH! I got this. First, you need the Pokemon you want to level up, put it into the daycare. Then, when you are about to go to sleep at night, go to Centrico Plaza in Lumiose City and then put something heavy on the left/right side on the arrow pad into somewhere open OR put a coin in the circle pad where you can use a bike so you keep going in a circle automatically. Then, you MUST plug in your charger into your DS and leave your DS open. Eventually, your Pokemon will keep leveling up and when you go to the daycare, your Pokemon will be high in level.

Source:https://m.youtube.com/watch?v=ILKagtJ6uQU

get a lucky egg and then train in high lvl places.