Oh, so they won't let me take the other path.

And I backtracked to Thunder Plains, it's not showing the enemies there too. How do I get it showing their names again? I want to be able to identify particular enemies and bosses if I have anything to say about them, or get help fighting them, etc.

Do you have someone with the ability Sensor on their weapon?

Several characters.

But I've figured out the problem. I was trying to take a picture of a battle with my favorite characters (Kimahri, Auron, and Rikku), and I hit Select by mistake, and that's what made their names disappear. I press Select again and their names come back.

Also, I get more experience from some of the enemies in the woods than Iron Giants so once again I might be delayed getting more levels.

Well, Spherimorph is quite the boss. The best way to defeat him is with magic, but he changes his affinity when you cast a spell and deal elemental danage on him. Perhaps you should read the wiki for better information about it. And perhaps even check some of Rikku's Mixes, they come in handy for many bosses battles.

Barrier Changing Boss like Hein, Melusine, and Magic Master?

Yup

I have been stealing lots of electric items from enemies, do those work for Mix? (Though if I remember, Rikku can only do that as an Overdrive)

Yes, they do. She can also use them in battle withe Special Use

That's individually though, without Mix. But I will remember to use those when his Water barrier is up. (Is Fish Scales the water equivalent of that?)

Also, it won't let me load the main page for this thread (likely due to length), so I'll start another one.

Edit: Wrong thread