how do I get a master ball in হৃদয় goth soul silver

Once আপনি beat Clair and get your badge, আপনি get a phone call from Professor Elm. Go to Elm's and আপনি get the Master Ball.

u find them sometimes, and sometimes people will give them as gifts. eather that, অথবা u can trade with someone with a bounch of them, and ask them 2 have some of the pokemon they trade hold a master ball.