The specially defensive set should run 252 HP / 96 Spe / 162 SDef. The extra speed EVs enable Mewtwo to outrun Lati@s. This means you can Taunt them before they Calm Mind, and then Light Screen before being hit by their second attack. This way, you will never be 2HKOed by a Modest Latios Dragon Pulse, and Draco Meter fails miserably.
