You should get the Master Ball by talking to the President of the Silph Co. in Safron City after you saved him by defeating Giovanni.
Have a friend trade you a Pokemon holding the master ball they received.
Master Ball
use a master ball on it
Only one
No unless you have a game shark
u cant
There is only one
to catch suicune,mewtwo,raikou and entei
Try to get a ultra ball
In Silph Co. in Saffron city. After you get to the top of the building.
You can only receive one master ball in leafgreen version its obtained from the president of Silph co after defeating team rocket and there boss.
You get it form the owner of the Silph Co building after you save him.