pal park
the guy from the team galactic gives you one to catch girantina in the distortion world
bad code
There is a socialite who only has a Roselia.
go to iron island. riley gives it to you at the entrance
in Platinum on your way to the spear tower the detective gives it to you in Mt Coronet. it is most likely the same in pearl.
cyrus gives it to you
Cyrus gives u one
you can not get a master ball in Pokemon platinum only the one professor Rowan gives you
2 the one Cyrus gives you and the one you can win at the veilstone game corner
the guy from the team galactic gives you one to catch girantina in the distortion world
beside solemn town's Pokemon healing centre there's a house and when you go in it there's a fat man that gives you a assignment and when you complete it you get a heart scale and a few poke balls.
theres a guy who gives you 5 of them if you show him a certain pokemon. hes thenews reporter guy in solaceon town. they dont start selling them until after the 7th or 8th badge.
someone gives it to you.
Cynthia's grandmother gives it to you.
jortan
Cynthia gives it to you.
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 :(