Mewtwo is a legendary Special Sweeper. It's primary goal is to take down the opponent's team with high-damaging special attacks. Life Orb boosts the power of Mewtwo's damaging moves by 1.3x but it then loses 1/10 its max HP immediately after the attack. With Pressure, if Mewtwo is the target of a foe's move that move loses one additional pp. This Psycho Killer Mewtwo Build is from Smogon.com "Simple" may be the first adjective to come to mind when discussing this set, but "strong" isn't too far behind. Once Mewtwo finds an opportunity to sneak in a Calm Mind, its massive Special Attack, Speed, and coverage will do the rest. Unless the opponent has one of the very few checks to Mewtwo, he or she will probably lose at least one Pokemon.The chosen moves give Mewtwo the best coverage in general. Psystrike works as a generic STAB move and is Mewtwo's best attack against Chansey, Blissey, Kyogre, and Ho-Oh; however its main draw is that it essentially allows Mewtwo to work as a mixed sweeper, since it calculates damage based on their Defense stat, while still working off Mewtwo's superior Special Attack. Ice Beam hits Lugia and the Giratina formes hard, while Fire Blast and Aura Sphere both thrash Steel-types who resist Psychic and Ice. The choice between Fire Blast and Aura Sphere depends on the threats you need to cover. Fire Blast will put the hurt on Jirachi, Bronzong, and Metagross while Aura Sphere dents Dialga, Tyranitar, Heatran, and Dark Arceus. It is worth noting however that Fire Blast is boosted by sun and weakened by rain. Depending on what weather you expect to battle in, you might want to emphasize or forgo Fire Blast. Finally, should coverage be your primary concern, you can use all four attacks without Calm Mind.