Rottweilers and German Shepherds would be good for obedience and maybe agility. I don't think beagles would be good at agility or obidience because they are hunting dogs. I saw one thing on TV about how they train K9 police dogs and it showed a German Shepherd going through an obstacle course and even climbing up ladders. Rottweilers are good at obedience but they are pretty big so i don't know about agility.