You can most likely use cheat codes, to obtain more Master balls, but that requires the action replay, and or (Game Shark?)....
you can only get one in the game without cheats
Have your friends trade you the master balls they got.
well the max of master balls you can get is 999 but you can only get more master balls in trades.
No
buy them at walmart
You trade Pokemon from friends that's Pokemon is holding a master ball
give one to a Pokemon and trade the Pokemon with the master ball.
more like 493 master balls. its a cheat on the AR look up the code for it. its called Pokemon modifier.
Pokemon lotery and action replay
use a game shark
action replay
Hacking