Tonight I tried getting one of the Legendaries in Diamond, I forget its name, but man that's a pain in the butt the way it keep running away. Do the other two do the same?

I still need to beat the Elite 4, but I can't make myself grind anymore. I have three traded Pokemons in my main team, so they level pretty fast, but for the ones I caught, it's just painful. And I have doubts that a team of 50s would make it through the Elite 4 without me wanting to cut my wrists on more than a few occassions.