I just gutted out my bathroom in the basement and the studs on the wall between the bathroom and the basement kitchen are not plumb. The wall itself is but the intermediate studs within the wall are not Is this something I can/should fix?
The wall is not load-bearing. The angle of the studs is not a structural problem, but they cannot be unseen. If it's going to bother you you can attempt to fix them.
To straighten those studs you'll need to detach the drywall. That's potentially messy. Maybe you can cut the drywall nails with a hacksaw blade, hammer the studs to the correct location then toe-nail the studs in position and finally glue the drywall to the studs. Or maybe you'll make a mess of the drywall, and have to fill some holes or replace it. To keep things interesting that cable and those boxes are going to complicate matters.
The problem you're likely to have in a bathroom with studs not being plumb is not left-to-right plumb, but in-out plumb.
That is, if you take a straight edge like a long level (four foot is okay, six foot if you have one) and hold it to the inside-the-room side of the studs (the "narrow" side for 2x4 studs), is the stud "flat".
Also, are the inside-the-room faces of the studs co-planar and parallel with each other?
Those two questions will affect your ability to hang tile, especially large-format tile, and mount fixtures like a medicine cabinet or a wall-mount mirror. Since you asked another question about a floating vanity, consider that the evenness of the wall will affect your ability to mount that vanity.
There are a few things you can do:
Use a hand plane, electric plane, angle grinder, or belt sander to remove material from the studs.
Use wood or plastic shims, or small hand-made wedges of some kind, to add thickness to the studs.
For cement-board walls, you can install the wall board then apply one or more layers of thinset mortar using a level or other long straight edge as a screed to achieve a flat wall.
Remember that "flat" is more important than "plumb." That is, a wall that is 88 degrees away from the floor but will not crack your mirror is much better than a wall that is 90 degrees away from the floor but has a big belly in it.