It works great
If you can add those options that would make it really flexible.
In the case of the power generators, you could define a state called "disabled" and during that time the invulnerability would be gone and so you could target the boss.
Of course, once they recover from that state you won't be able to target him again.
To make such a battle more complicated, I could make the generators immortal, and some player would have to disable them again and again just to beat the boss.
On top of that, is it possible to make it so that you simply cannot select any enemies and must defend?
Like in old final fantasy games you have a dragoon that jumps into the air and you can't target him until he comes back down, even if he's the last guy.