In Black i was stuck on the second gym leader.
Because her pokemon one shots everything I could get, until I got a SECOND fighting type and level'd him up to 20.
20 was the max I could make a pokemon without it not obeying. The gym leader has a level loving 21 that uses Thrash, and for some reason it kills everything in one hit. I managed to beat it by sheer luck.
Then i quit playing because i couldn't take it anymore.