Even with status it's just a matter of luck and patience - just keep at it. But certainly main tips would be to get their health down as low as possible, and try a status - paralysis is decent as it lasts forever unless they have Rest/Refresh or something, but Sleep is the best status to use as it increases the chance of catching a Pokemon by the most. (So does Freezing but...yeah).
As for the legendary dogs, either Master Ball, dumb luck (hey it happens =p) or chasing them down the old fashioned way. Moves like Mean Look, etc will stop them running away, but Roar is still there - however there are ways around that still if you are clever about it and have the Pokemon for it - say Baton Passing Umbreon with Mean Look to say a Pokemon with Soundproof as an ability - baton passing the Mean Look keeps them there and soundproof stops Roar from working.
Anyways going to close then - any other questions, please ask them in the Help thread sticky at the top of the section.