It depends.
It helps to get it with on HP by using Hyperfang or false swipe and you make it paraylzed or frozen.
Also save before trying to catch ANY legendary JUST IN CASE it faints so you can just turn the power off and retry.
Use an Ultra Ball, not a Master Ball
I caught it with an ultra ball. Best is to lower it's HP and catch it or put him to sleep. but you need 10-15 ultra balls or more. Depends on his HP.
You would need to get the Action Relplay at GameStop.
other than a masterball probaly with a hacked ball cherish or ultra,timer,heal,and quick ball
Using a Great Ball is the best way. Actually a Ultra ball is the best way.
Yes it can, it would be easier to catch Registeel with a Ultra Ball than with a normal PokéBall.
The best pokeball to catch registeel is a repeat ball if you have owned a registeel before trust me it will work wonders for you i caught registeel with a repeat ball without even weakning it.
master ball
Weaken it then use many great balls or pokeballs or timerballs if you own a registeel from a friend try using a repeat ball. This is no joke when i tried to catch registeel i already owned one from a friend and i just threw a repeat ball and i caught it on the first try.
Ultra ball.
Yes. It is completely possible to catch Mewtwo with an ultra ball.
a quick ball or a master ball
No. They have the same catch rate as all the other legendary Pokemon. However, they are all in caves, so you can use a dusk ball which has twice the catch rate as an ultra ball (only in caves or at night) and is 200 poke-currency cheaper than an ultra ball. You could still get lucky with an ultra ball, but if I was using ultra balls, I would bring at least 40 of them, a Pokemon with hypnosis (or some equivalent), maybe false swipe, and save before you try! You could probably be fine with just 30 dusk balls.
ultra ball
get a ultra ball lower its hp to half and throw the ultra ball
1st:Throw the Ultra Ball 2nd:See if it catches it Easy.
NO! I recommend a dusk ball!