The drawback to the OU pokemon is that their move sets aren't very diverse. Aside from hitting hard and having 600 stats they really don't have many effects, just kinda smash and go. Given that, when you encounter a wall like Skarmory or Claydol there's just not too much you can do, and even if you did have some sort of trump card your opponent knows what's coming since those pokemon are so common.
They're strong pokemon, and OUs are definitely worth of seeing serious play, but their strengths really bleed through when they're shuffled in with a more diverse crowd. With a well balanced team the game is more adapting, responding, and trumping your opponent. Creativity is golden I guess is what I'm saying. Let me know if I can help at all, you definitely have admirable motivation.
If it's any consolation, no one else has beaten me either.