Can you cath Mewtwo without a master ball?

Yes, it is possible to catch a wild Mewtwo without using a Master Ball. Mewtwo can be found in caves of Cerulean on Pokemon Blue and Red. In order to catch Mewtwo, you must get it below half of its health in Pokemon Blue and Red. Using attacks like thunder wave paralysis and putting the Pokemon to sleep will allow for more effective captures. You will need to throw multiple ultra ball until the Pokemon is captured. However, it is more likely to capture a Mewtwo with a master ball.