beat the elite four serveral times, then go to cecilian cave ( i spelt it wrong sorry) You should save your master ball ONLY for mewto.
you can't get mewtwo in Ruby, Saphire, or Emerald without trading it from another game.
mewto
You can catch MEWTWO ,not Mewto, at the end of Cerulean cave
I don't really know but i think you have to have an Action Replay to get mewto lr you have to transfer it from an older Pokemon
action replay
Unfortuenetly u cant catch mewto on emerald only on fire red.green and dimond and pearl! SORRY SUCKERS!!!!!!!
no
trade it
PIKACHU
Yes
mewto
Cerulean Cave.
back of cerulean cave