The Phenomenal One wrote...
So I beat the game [the main story, at least] last night, and I am
not a happy camper. The ending was cool, it's just when I got back home, the shit started. I get my National Dex after a certain character makes a guest appearance and I fly off to Opelucid City to head on out to Route 11 and beyond, and what do I come to find?
That all the trainers from Route 11 and beyond have Pokemon that are 10+ levels stronger than my current party. Now I have to backtrack to beat all the trainers that I missed [i.e.-Trainers that you can only reach via HM.] and/or grind to 60 after I just got done grinding to 50 so I could beat Ghetsis.
...
FFFFFFFFFFFFFFFFFFFFFFFFFFFUUUUUUUUUUUUUUUUUUUUUUUUUU- /ragequit
Actually, from my own experience, you should have no trouble with them even at your current levels. I know I've beaten most of them without any true trouble. There are a few more tricky opponents, but even they can be beaten with a couple of your Pokémon still surviving the battle.