Where is Mewtwo in cerulean cave?

Answer 1

Be sure to stock up on repels, and make sure you have a Pokemon that knows flash! HMs and TMs needed: TM flash, HM surf. Okay, now you're ready. When you get inside, have your Pokemon knowing flash use it. Then go to the water and use surf. Go straight until you see the wall and turn left. Go under the bridge and go down. Shortly after, go left and find the small staircase. Go up the stairs. IGNORE BOTH LADDERS! Go past the ladders and down the stairs and turn right. Walk up the stairs and turn right. Follow the pathway until you reach the ladder. Turn left and walk down the stairs. Pass under the bridge and follow the pathway until you reach the large set of stairs. Walk up the stairs and climb the ladder. After that, go left and you will come to a split road. Take the top road and when you get to the the next split road take the right one. Follow it and go down both ladders. Follow the path until you come to a body of water. Use surf and go right. Follow the right pathway until you come ashore. Follow the upward path until you find a body of water. Use surf and turn right on your first split in the path. Land ashore, go up the stairs, up the ladder, and congrats. You have found him. Good luck!

Answer 2

You can NOT catch mew in there. But you can catch mewtwo. do not look it up on YouTube. THEY LIE!!! you can only get mew on a DS event (2011 and so on)