Well first you have to find it and battle it but before you do that you need a Pokemon with areena trap or or shadow tag Pokemon with areena trap are dugtio diglett and trapinch and Pokemon with shadow tag are wynut and wobuffet so catch one of those and level it up to about level 47 48 or 49 get mesprit down to red hp then use some ultra balls and if its night dusk balls might work too.
A Master Ball
Its hard, but try catching it at night when dusk balls work. hope this helps
Mesprit or Cressalia. They are both running Pokemon, so they are very hard to catch.
Use Electric Types To Paralyze The Get The Life Low And Use Ultra Or Great Ball.
no
jiroxy ball...
Use a quick ball and hope- but if it doesn't work it will flee
you have to trick it to come to you, then it will only stay with you for 1 turn so use a master ball.
Normally you need an AR, or a master ball, because once I had mesprit at 1 health and I couldn't catch it so don't try.
I'm not quite sure what your talking about, but I would have to say that you would not have to catch it in a Master Ball.
Yes
you need to have two master balls.