That depends on the Pokemon game.
You can NOT get 99 Master Balls unless you have a gameshark.
cheat codes or gameshark
Here is the (M) code00000554000A101DC9B00007830050000000830050020000when you use the code you will have 99 of all balls including (master balls and safari balls)420259D800010001000C0004420259DA52120000000C0004
Add "01017CCF" to the emulator's Gameshark cheat list. You can now buy 99 Master Balls for free in any mart.
unfortunately you can't get 99 or even just 2 master balls but you can get 1st at silph co in saphron city.
look in all the bin's on the first three city's and there's 99 master ball's in one I think.
go to oak and press L
action replay
you can't
You have to have gameshark to get 99 masterballs. Gameshark is a cheating system that allows you to type in codes and get/do certain things. the pokemon firered masterball code is: master code:000014D1 000A 10044EC8 0007 masterball code:82003884 0001
you can only get 1 master ball per game
My geuss is the ds game shark.