Hell Sauron has hypnotised whole teams plenty of times. It what he does.
When he has a mutie like Wolverine to suck a bunch of energy out of..well there you go.
Iron Man did mop the floor with a bunch of guys in the Savage land after all that happend.
What would happen if Sauron hypnotised Superman? He'd be giving the whole JLA trouble 😛.
And let's not pretend Superman has never been mind controlled.