By the way, everyone playing this: do the victini event. But don't catch it. That fucker gives out 600ish exp a pop. I evolved my Sandile to it's second form on that bastard. You can easily, easily get even non traded pokemon up to around level 26 with just repeated kills of victini and save yourself a hell of a lot of aimless wandering through the grass.
This is made even easier by the fact that inside the lighthouse, by the entrance, is an old man who will fully heal your pokemon like a pokemon center.