Is leveling the HB Mewtwo to level 50 worth it? Or should I stay with the one that hits the same Skill Rate at level 30?

Was about to start using candy boost on the Mewtwo before I realized that I ideally won't be using Mewtwo the whole week. She just needs to be on the team long enough to trigger her skill to max and then i switch it out. Made me Wonder if investing into a Mewtwo that's better later even the right call or if I should just spend my candy boost elsewhere and use the other one that reaches 4.3% at level 30?

I have sub seeds so assume skill trigger and speed subs have been promoted.