You want to hatch eggs. Whether it's for IV's, new pokemon, duplicating starters, whatever...
step 1: grab a thread, bag, etc... anything that can wrap around the thumbstick of your 3ds
step 2: Head over to lumiose city, (the way the camera follows you makes this possible)
step 3: grab your string or whatever you have, grab your eggs, wrap the string around your thumbstick,
step 4: hang enough weight from the string/thread to pull the thumbstick, but not too heavy (you don't want it to pull your 3ds off of the table)
step 5: go to one of the boulevards in lumiose, (jump on your bike) and let the weight down softly (this should pull the stick and cause your character to go in circles)
Step 6: go do your thing and come back to check for the "Oh!" message!
step 7: be happy that you didn't have to sit there the whole time and do this -_-
EDIT: looking around the internet, I've seen a lot of different ways, but this one is the best I've found/seen so far.
the only thing that is a bit better is that you can use a dime to wedge the thumbstick!
Happy hatching! ^____^