No, you do not have to catch all the Pokemon to encounter Mewtwo. Mewtwo can be found in Unknown Dungeon/Cerulean Cave in the first Generation games at the deepest part of the cave after beating the Elite Four and the Champion of Kanto.
Catch 'em all
how do you catch a mewtwo on Pokemon platinum
No you can't catch Mewtwo in Pokemon silver, you must trade it from Pokemon yellow.
You can catch Mewtwo in Pokemon HGSS after you have beaten all Kanto gym leaders then you may fight or catch it at the end of Cerulean Cave, Mewtwo is found at Lv.70
You can't catch Mewtwo in Pokemon Diamond and pearl and also platinum. But you can catch Mewtwo in heartgold and soul silver
can only get mewtwo through trade in Pokemon emerald
you cant catch mewtwo in Pokemon platinum peral diamond you can in Pokemon heart gold and solsilver in canalave cave
mewtwo
There is no such Pokemon as "Shadow" mewtwo. There is a regular mewtwo that you can catch like any other Pokemon. It's located in the Cerulean Caves.
To Catch Mewtwo You Need A Action Replay.
cerulcean caveyou catch mewtwo in the cerluan cave (its wrong spelling)
any strong Pokemon