From what it looks like now, you can't get more then 1 Master Ball in any Pokemon game.
However, you can trade them over to another Pokemon game.
Example : If you need a Master Ball on Platinum, you can still trade it over from Diamond and/or Pearl, or even from HeartGold and SoulSilver.
I'm afraid that's the only option to get more then 1 Master Ball.
You cannot find a second master ball however you can trade Pokemon to get another Pokemon with a master ball or use an action replay
go to the 4 island give a master ball to one of your Pokemon put ditto in breed it the Pokemon that hatched will come out has a master bal
Every Pokemon can be caught without a master ball. And just because you verse a legendary doesn't mean it has to be caught with a master ball. Because I caught a Ho-oh in a Poke Ball.(In Soulsilver). I ACTUALLY DID SO I DID!!!!!!!!!!!! and when i was in Pokemon platinum i caught dialga and palkia with an ultra ball on my second try.HE ACTUALLY DID SO HE DID!!!!!!!!!!!!!Thank you for spending your time on this question. :)Also, I'd recommend saving your masterball for Cresselia, as she always flees from battle.
if you beat the boss of team galactic, you will get a master ball from him
it is not if you use a net ball twiceResponse from creator: I tried every single kind of pokeball there is in Pokemon Platinum at least five times except a master ball. Which means i tried the net ball at least five times, i still didn't catch him therefore, until there is an answer that actually works, i still think Heatran is impossible to catch and i still ask why. WHY!?
in every pokemon game you get one master ball before the leauge
Yes. You can trade with someone that has a Pokemon holding a master ball.
no the master ball works strait away without doing anything to the Pokemon
It's the most powerfull pokéball ever. You can catch EVERY wild pokémon with it without fail.
you have to save the president of silph co. to get the master ball.
You trade Pokemon from friends that's Pokemon is holding a master ball
Clone your Pokemon and give them the master ball
give one to a Pokemon and trade the Pokemon with the master ball.
Use a master ball.
Of course, a Master Ball catches any Pokemon without fail, Legendary or not.
You Can"t You Need To Get A Master Ball Hope This Helps :]
Make a Pokemon hold the master ball then clone that Pokemon.