Im pretty sure you have to use an action replay or a GameShark for mew, but to get mewtwo you have to of completed the elite four, west from cerulean city theres a cave with a male or female waiting outside make your way through the cave and you will eventually get to mewtwo, personally i saved my master ball for mewtwo i would recommend this its less hassle trust me!
Chat with our AI personalities
You can't get a Mew unless you cheat, I think. A Mewtwo you can only catch in Fire Red\Leaf Green and transfer to your Pearl.
um listen Pokemon fire red does not have mew only mewtwo and that's in cerulean cave
you can't get mew in leaf green you get it in fire red
You cannot catch Mewtwo in Pokemon Crystal, but you can trade it from a Pokemon Red or Blue. Hope this helped :)
No, Mewtwo cannot be caught in Pokemon Crystal. It can, however, be traded from Pokemon Red, Blue, or Yellow.