using mew2 against mew2 tomorrow, PC vs Confusion

PC is better against psychic Pokemon since confusion and PC are resisted and SB is SE. confusion really doesn't have high dps against M2.

Definitely psycho cut. Since both moves are resisted by Mewtwo, you'll want PC due to it's higher energy gain, allowing you to fire off more Shadow Balls.

1) Mewtwo with Shadow Ball is good against any Mewtwo moveset except SB. Resists Psychic, neutral against Focus Blast and Hyperbeam.

2) Using Psycho Cut as your quick attack will not only get more energy for those SBs, but will also allow you a better possibility of dodging if you're so inclined.