Myuutsū is an evolution of the Mewtwo project, essentially "Mewtwo 2.0," if you will. He's not psychically more powerful, as the peak of psychic potential was already achieved with Mewtwo. Instead, his physical capacities have been massively enhanced.

He is 11'06'' or 3.5 m tall and weighs 3,219 lbs or 1,460 kg.

Weight comes from this figure here, but with modifications: https://www.serebii.net/letsgopikac.....emonsize.shtml

The Mewtwo 2.0 project has led to much more dense musculature and bone density. It gives the Mewtwo incredible strength and endurance without actually taking away its agility by keeping the body relatively compact. To simulate this, I have taken the minimum size and weight of 1.2m and 36.6 kg and boosted the weight up to 55 kg, and then scaled up in accordance with the intended size.

As for the height figure: https://db.pokemongohub.net/pokemon/150

According to the master file of Pokémon GO, the largest possible Mewtwo to be encountered in the game, although with astronomically small chances, is 3.5 m.

Pictures provided by  livinlovindude

Scale chart: macrovision.crux.sexy