You have to get the National Pokédex by catching at least 60 different types of Pokémon and talking to Professor Oak, and then deliver the Ruby and Sapphire stones to Celio on Island One. You can then enter Cerulean Cave.
Beat the elite four and if he is still there obtain at least 60 pokemon data
Get the national dex and beat the elite 4.
You Have To Beat The Elite 4 First,Which Is Hard.Once You Beat The Elite 4,The Guard Is Next To The Entrence To Cerulean Cave,And Your On The Road To Getting Mewto! YOU NEED TO BEAT ELITE FOUR.. AND HAVE 60 POKE's TO OBTAIN NATIONAL POKEDEX... AND POPPED>.!! THE GUARD WILL BE NEXT TO THE ENTRANCE OF THE CAVE..
Use Surf on Route 24 then go south you should see a huge cave that's cerulean cave if the cave isn't open you must beat the elite four.
If you want to catch Mewtwo in Soulsilver , first , beat the elite four, then get all 8 badges in the Kanto region, then you beat red at the top of Mt. silver, after that fly to Cerulean city in kanto, go to route 24 and surf to the cave in cerulean. Deep in that cave is where you find mewtwo!
After you beat the Elite Four.
You have to beat the Elite Four once.
Beat the elite Four
you can catch mewtwo in cerulean cave in cerulean city but first you have to beat the elite four
Beat the elite four and if he is still there obtain at least 60 pokemon data
you have to beat the elite four, and get the national dex. then go to cerulean city, go past the nugget bridge, and surf on the water. there is a cave,and its cerulean cave
You must beat the elite four first, then you can enter.
yes it should be
You have to beat the elite four and complete your pokedex.
Beat the elite four.
Get the national dex and beat the elite 4.
first u have to beat the elite four and get the ruby and Sapphire then you can get into the cave to catch mewtwo