it is in team aqua's base (the one where they had the submarine)
in team aqua's hideout in lilycove city
you can get a master ball by winning the lottery in lilycove
In the Aqua Hideout.
Right of Lilicove
you can if you have a Master Ball
In lotto
GO TO THE MOON AND USE A MASTER BALL ON IT. Go to the moon and use a master ball on it and save the game.
die
You get the Master Ball in the Aqua base off of Lilycove. It is in an area with two Electrodes and one Gold Nugget.
It's hidden in Team Aqua's hideout.
In the office of team Aqua's hideout.
throw a master ball