Steps to getting Mewtwo in FireRed/LeafGreen?

Question

What are the steps to getting Mewtwo in FRLG? I've already got the National Pokedex, but don't I have to get some jewel for Celio? How do I do this?

Answer 1

Step 1: Beat the Elite 4.
Step 2: Obtain the national dex.
Step 3: Find and fix the network machine by finding the ruby and sapphire stones. You must search through islands 1 and 6 in order to find the ruby and sapphire. Once you have it all, return to island 1.

Answer 2

WikiHow has an extensive guide on this topic.