Well, it depends on which game it is. In Pokemon Diamond, you can get it after you defeat the team rocket or something. In Pokemon Soul Silver, you can get it by winning the lottery. You get the point. Until you specify your question, i wont be able to answer it directly.
Yes, if you have a Pokemon hold a Master Ball and then trade the Pokemon, you will have transfered the Master Ball.
trade a friend a pokemon and his pokemon holding a master ball
where do you get the second master ball in Pokemon pearl
No, there's no Master Ball available at Pokemon Centers.
no it won't be holding a master ball cos when you used the master ball to catch a certain Pokemon, the master ball will be gone in your inventory because it is a consumable.
No, you don't get it back.
Yes, you can get a master ball in Pokemon black. You get the master ball towards your last gym battle from Prof. Juniper =)
You can get one Master Ball in your GBA game and then migrate to Pokemon Pearl with a Pokemon holding the Master Ball.
No.
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
Have a friend trade you a Pokemon holding the master ball they got.
you could save before getting it, get the master ball, have a Pokemon hold it, trade that Pokemon, turn game off then back on, get another master ball, and trade Pokemon back.