How do you catch Mewtwo?

Mewtwo can be found in Cerulean Cave after you have defeated the Elite Four, have obtained the National Pokedex, and have fixed Celio's Machine on One Island. It might be smart to save the Masterball for Mewtwo.

Any Party will do. You can defeat the Game with any Party. I would suggest to have Dragonite, Charizard, Mr.Mime, Primeape, Nidoking, and Gyarados. I did really go with this team.

Hope this helps!

Mewtwo- beat Elite Four and I finished the islands then caught Mewtwo but I've only ever caught him with a masterball
The game is beatable with almost any party, I used Raichu, Lapras, Hypno, Gengar, Venusaur, and Arcanine

My team did pretty freaking awesome and I just used arcanine, alakazam, blastoise, Zapdos, snorlax and golem. You can get away with the first four and beat the Elite Four fairly easily. Movesets are as follows: Arcanine-extremespeed, flamethrower, fire blast, sunny day. Blastoise-skullbash, Surf, hydrocannon(not hydropump, this is better, and ice beam. Zapdos-drill peck, thunderbolt(Game Corner), thunder, Fly(pretty much useless since we have drill peck but I needed a flyer). Alakazam-shadow ball, psychic, calm mind, recover. Snorlax-toxic, body slam, rest, snore. Golem-earthquake, rockslide, double-edge(best if you have rockhead to prevent recoil), explosion. Hope that helps. I breezed through the elite four after struggling a little the first two times.

Ok my best before elite 4 was bef. Venasaur,Moltres,Pikachu,butterfree,kingler,and dragonite now for the after. Everyone but butterfree she was switched with Mewtwo my move list was venasaur(solorbeam,Cut,hyperbeam,synthsis ether use hyperbeam of frenzy plant),moltres(flamethrower,Fly,overheat,sunnyday),pikachu(thunderbolt,thunder,iron tail,dig),dragonite(hyperbeam,Waterfall,Strength,outrage),kingler(icebeam,crabhammer,hyperbeam,Surf)(now this is butterfree k psybeam,confusion,shadowball,silverwid),mewtwo(psychic,safeguard,recover,swift)thats I'm chaovincent I caught the mewtwo with an ultra ball

I caught Mewtwo with 6 ultra balls. I just froze him with ice beam