I have gone through the victory road and my Pokemons are around lv 47, I want to get them up to lv 55 but what is the fastest way to train?
Torterra lv 47
Lucario lv 47
Garchomp lv 48
Gengar lv 48
Vaporeon lv 47
Staraptor lv 47
First Exp share one of your Pokemon (i think you get one from somewhere) then get a lucky egg (i dont know if it was introduced in gen 5 or not). Also I think you should try to train at victory road and I know it sounds wierd but if your Pokemon can beat barry at the elite 4 Pokemon center you may want to "commit suicide" by battling the elite 4s with NO ITEMS that way you only lose money (only if your desperate because you lose a good sum of money)
Other than that I cannot help you unless I say GET TRADED POKEMON they train faster for some reason and its really effective (hope you have internet connection or a good friend with some good Pokemon)
Train in Victory Road and around The Pokemon League. They give you the most EXP up to that point.
Well,i would suggest you to battle some Pokemon in victory road as they give a lot of exps.
I'd go back to the last town and train by the nearest route there. Then, when oyur Pokemon are arount 50 or 51, train at Victory Road. It'll be simple, trust me. Do this until all your Pokemon are level 55 or higher.