Go back the way you came through vic. road, until you get to the room with a doctor in it. Inside, train by battling Durant(these give the most exp), Boldore, and Excadrill. That's how I got to level 60.
I know, but I still have a long way's to go until they're level 50 because they don't level up as fast as I would like them to...
What kind of poke. did you use to beat them?
I tried challenging the dark, and fighting type pokemon with level 30's and one level 40...I lost miserably last night when I tried challenging them I could only knock down one pokemon...