Most people, it would seem, use it on Dialga (or Palkia in Pearl). It isn't necessary; unlike in other games, there isn't a single Pokemon that you must have it to catch.
I would suggest saving it for Mesprit or Cresselia if you don't want a big hassle chasing them down over and over, but they are quite simple to catch otherwise.
Giratina would be a good candidate, as it is extremely hard to catch (though I caught mine with a Timer Ball after quite a long battle).
It really depends on whether you mind a long battle or not. I caught Mesprit and Cresselia with very little fuss using Ultra Balls, but Giratina took a long time. If you don't mind hunting down Mesprit and Cresselia, I'd save it for Giratina.
Or in my opinion you could use it on Darkrai as it is very hard to catch with any other ball (even though i the Pokemon master caught it with a pokeball)
I suggest donot use it on kyogre because i already caught him with an ultra ball so i would probably use it on latias or latios because they fled right away and once they fled its hard to find them again. so the master ball cant fail so i would use it on one of those. and this is also the same for ruby and emerald, except ruby dont use it for groudon and emerald dont use it for groudon. because latias and latios are in emerald ruby and sapphire. so id say which ever one you find first whether its latios or latias i would catch that one, and i dont dont think youll catch both unless you trade. and dont try to weaken latias or laios because when its there turn to attack they fled, so just use your masterball right away when you find it.
It's best not to use it, due to you only get one Master Ball. But, the Pokémon you should really use it on are legendaries (not Victini or any other legendary under level 40). But what a lot of people do instead is trying to catch all the Pokémon in Pokéballs (or any other ball apart from a Master Ball) to show off their skill. Plus, wouldn't it have been nice to catch Zekrom/Reshiram in a Pokéball?
After defeating Cyrus in Veilstone, he should give a Master Ball to you.
giratina
Master Ball
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
no
probaby kyogre
yes u can in all pokemon games
You cant
The trick is to save your master ball.
profecer elm givs it 2 u
To get an additional master ball, you must either trade it from another Pokemon game, or use cheats to get one.
one of the monks in the bell toweer will give you it
You have to fight it until its weak then use a master ball
I sugest using master ball... that's how i caught it
After you beat Lance, go back to professor Elm and talk to him. Then, he'll give you the master ball! (You can go to pokemon.marriland.com.)
1. start a new game then trade it from that game 2. Mirgrate a Pokemon holding it