yes it is possible but very very hard
First of all you need to save before you start so that you can try again when you mess up. Then get about over 30 ultra balls and get it to the point where the mewtwo is almost fainted. Make sure the pokemon is not dizzy or poisoned. Just keep throwing ultra balls at the mewtwo and make sure YOUR pokemon is strong too. It is better if you make the pokemon sleep.
the masterball is for any Pokemon you want, it can catch them without fail ( it will ALLWAYS work ) . you are supposed to use it for mewtwo though. :P
Use you masterball on suicune because its impossible to catch it without a masterball it would just flee i cuaght mewtwo with a great ball but make sure you have lots of them.
Congrats, you're done with the game. There's really no story after Mewtwo.
mewtwo is in cerulean cave. the cave in in cerulean city, where misty's gym is. mewtwo in hard to catch, though.
you can catch mewtwo at cerulean cave
you have to save your masterball no matter what and use it on mewtwo in order to catch it faster. otherwise, you are going to spend hours trying to catch it without any luck.
the masterball is for any Pokemon you want, it can catch them without fail ( it will ALLWAYS work ) . you are supposed to use it for mewtwo though. :P
Use you masterball on suicune because its impossible to catch it without a masterball it would just flee i cuaght mewtwo with a great ball but make sure you have lots of them.
With a Masterball
MasterBall
Try to catch it with a masterball. that's what i did.
masterball
1. you cant catch mewtwo on ruby emerald or saphire<spelling mistake> you can migrate the mewtwo you catch on leafgreen or firered to migrate to platinum
masterball
It isn't meant for any one pokemon. Most people use it on Mewtwo, which you probably should use it on. You can catch the legendary birds and Mewtwo without a Masterball but it can take a long time.
Lv70
the strongest pokeball is the masterball. the masterball can catch any Pokemon out of the 493. it doesnt matter what kind of Pokemon it is, the masterball can catch any Pokemon.