use it any Pokemon that u have trouble catching u don't need it to catch mesprit or cresslina i used pokeball
After defeating Cyrus in Veilstone, he should give a Master Ball to you.
master ball
no
you can not get a master ball in Pokemon platinum only the one professor Rowan gives you
you cant get a second master ball in any game. The only one is given to you by Cyrus. If you have leafgreen etc. you can give one to a Pokemon to hold then transfer it to platinum by pal park.
there is no more masterballs in Pokemon platinum but not if you use cheats
with a master ball or timer ball
with a master ball
Master Ball.
You should use it on cresselia or mesprit because they run away
Master ball
You should use it on one of the 'roaming' pokemon, like Cresselia in Diamond/Pearl/Platinum.