You can get unlimited Master Balls in the game without cheating, but the odds are very, very low. The only one that you can definitely get is found in Team Aqua's hideout in Lilycove City. After that, the only way to get another Master Ball in the game is through the Lilycove Department Store's lottery drawing; if the ID number of any of your Pokémon matches all 5 numbers of the number drawn in the lottery, then you are rewarded with a Master Ball. The odds of this, however, are 100000 to 1, but you can increase those odds with every Pokémon you trade for.
kaleb's cheating device.
Clone your Pokemon and give them the master ball
Make a Pokemon hold the master ball then clone that Pokemon.
You don't, because entering codes is cheating. I mean, look at me, I am the No.1 Pokemon Master and I never cheated. EVER.
Yes. You can trade with someone that has a Pokemon holding a master ball.
you can't
you have to save the president of silph co. to get the master ball.
You cannot buy master balls. You get one after a landmark event in the game (Not sure which, but it is in every game), usually from the professor. Do not waste it, because it is the only masterball you will ever get in that game without trading or cheating.
$#@! no
That is impossible.
Give your Master Ball to a Pokemon to hold, then clone it in Emerald with the cloning glitch.
One way is to play the lottery at the Lilycove Department Store. You will be more likely to win if you trade Pokemon with a lot of different game cartridges (different ID numbers). You need to have a Pokemon with the exact ID number as the one drawn in the lottery to get a Master Ball. You can play the lottery once per day. Another way, if you have another game cartridge, is to start a new game on it, get up to the point where you get the master ball, make a Pokemon hold the master ball, and trade for the Pokemon with your first game. Repeat for each additional Master Ball you want. A third way, if you have access to a Pokemon Emerald cartridge that has beaten the game and not used the Master Ball, is to clone it. Google "Pokemon emerald cloning glitch". This method requires no cheating devices, but exploits a glitch and is considered cheating by some people. If you are one of them, do not use this method. You can trade the cloned master balls to your Ruby cartridge by making Pokemon hold them.