Can 16 year old kids also work out with a parent if not do you know were I can find a gym that does

A sixteen year old can work out with a membership at 24 hour fitness alone or with a parent.

Yes

There is a Kidz Klub at many locations, too....complete with structured programs if desired & always with supervision.

I signed up at age 17, didn't go with a parent so the sales representative suggested a pre- paid visa card from(walmart/target) and school i.d. and that was it.

I'm pretty sure they can. I have seen high schoolers there. Some even got personal training.

I believe so. I think they just need parents permission