How many tyranitars do you need for mewtwo? how long lasts a mewtwo raid?

I've pulled two om my tyranitars to 3400-3500CP. The rest of my team is semi glassy;
Gengar 2400
Scizor 2500
Pinsir 2400
Snorlax 3000 (A)
It should give me around 120s+46s(A).

Wondering about pulling up a 89% tyranitar from lvl 20 to 3400CP; replace snorlax. would give me around -15s (150 in total).

Or is it not really necessary?