MewTwo

Psycho cutter fang breath.

Now serious, i think it depends on the trainers playing style. For me it would me Psycho cut because i like to dodge and is gives more EPS but given the fact that mewtwo is more tanky than Alakazam, one might choose for raw dps and wants Confusion.

In short
Raw dps: Confusion
Better dodging and charging charge move faster: Psycho cut

I like confusion with shadow ball. This is more of a general attacker moveset, so you go with max dps.

If I'm using focus blast, its likely against something where fighting is super effective, so I want psycho cut for the extra energy.

Psycho Cut, because Mewtwo isn't as tanky as Dragonite.

Cant you read his page?