This will only help you if you have XY, but if you have a buddy with a 3DS or if you have a second 3DS then just trade it over to XY and put it in the Daycare. Then, just go to the center of Lumios City and make your character move in circles non-stop (While riding a bike) and tape down the d-pad. Then, go to sleep and when you wake up, you have a high level Pokemon! now you just trade it back to ORAS and voila.
What I just said may be a little complicated, so I provided a video that shows the XY part.
Hope I Helped!
Source: Experience and YouTube