Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
I know, but you now know my Kyogre is scarfed so you could play around it more easily. If you just make the excact same switches and use the same moves until the part were Mewtwo is facing Kyogre it'll be okay.