at the Pokemon lottery in jubilife city if your lottery number corresponds to the id of your Pokemon
Hacking
Pokemon lotery and action replay
In Pokemon Diamond, Pearl and Platinum you can get one master ball from Master Cyrus. To get more, you have to cheat using a Action Replay DS or DSI, or you can trade Pokemon with your friends and receive master balls from the Pokemon that they traded.
Cyrus gives you one. but apart from that the only way to get other master balls is by winning the lottery If you want to get more than one you will need to get two ds's or borrow one, have more than one Pokemon ds game (Pokemon pearl, diamond or another platinum) and you need to get one of Cyrus then trade a Pokemon (I'd recommend a low lv Pokemon that you don't care about and make sure you trade your favourite Pokemon onto the other game) and make sure its holding your master ball and then delete your save on Pokemon platinum (that's why you need to trade your favourite Pokemon) and start a new file then get up to the part where Cyrus gives you a master ball and repeat this over and over again (it does take a while but its worth it) when you do that you can get more than one master ball and when you are happy with the number of master balls trade one Pokemon onto platinum whilst it's holding the master ball and repeat until all your master balls are on platinum or you can 999 master balls of the action replay ds using one of the cheats enjoy ;) he never gave me a master ball :(
you can only get one you have to beat Cyrus in the distortion world to get more you have to use an action replay code
there is no more masterballs in Pokemon platinum but not if you use cheats
Have your friends trade you the master balls they got.
As far as I know the only way to get more than one is on action replay. If you are trying to catch legendaries, other poke balls will work.
well the max of master balls you can get is 999 but you can only get more master balls in trades.
No
buy them at walmart
give one to a Pokemon and trade the Pokemon with the master ball.