There's a few things which can make it easier to catch high level pokemon (Or any pokemon for that matter):
1. Try make it's health as low as possible. (A good move to assist with this is false swipe - will not kill the pokemon under any circumstance, only leaves it on as little as one health point).
2. Status modifier. Paralysis is best, followed by sleep. This greatly increases the percent chance to catch it.
3. Ultra Balls or better. Ultra ball has 4x the chance to catch pokemon as a usual pokeball. You may want to use specialized balls, depending on what you're catching.
4. The move Mean Look can stop the pokemon from fleeing battle.
5. Don't let the pokemon hurt itself. Work quickly, if the opponent runs out of moves, it will Struggle and most likely kill itself with recoil. The move Disable can also useful to prevent recoil damage moves, but you need some luck there.
1. Try make it's health as low as possible. (A good move to assist with this is false swipe - will not kill the pokemon under any circumstance, only leaves it on as little as one health point).
2. Status modifier. Paralysis is best, followed by sleep. This greatly increases the percent chance to catch it.
3. Ultra Balls or better. Ultra ball has 4x the chance to catch pokemon as a usual pokeball. You may want to use specialized balls, depending on what you're catching.
4. The move Mean Look can stop the pokemon from fleeing battle.
5. Don't let the pokemon hurt itself. Work quickly, if the opponent runs out of moves, it will Struggle and most likely kill itself with recoil. The move Disable can also useful to prevent recoil damage moves, but you need some luck there.
