Is a 91% Scizor with bullet punch and night slash worthy of a charge tm?

What level is it? Not worth it if a ton of stardust will be required.

Iron head and night slash are both charge moves.

IMO, only if the following apply, it has a perfect attack IV, isn't too low level, and you need it for lapras raids. It would have been useful for Articuno as well, but that one is gone. Other than that, you want a FC/XS as a Mewtwo counter.

Of course. I've power up IV95% to Level36.5, it's a super attacker!! you might need him as well for Mewto Counter, I spend two charge TM from BP to X.

I have a Scizor with Bullet Punch / Iron Head :
I used it in Articuno Raids (Super affective and Resist Ice attacks), He is also good against Tyranitar.
You can also change his attack to bug type to counter Psychic Pokemons (Alakazam,Mewtwo,...)