Do both Superman enemies have to have line of sight to enemy fig to use outwit on it?

No.

It's really simple. The one that costs more, or the controller's choice if they're the same cost, gets Outwit.

As long as the two figures remain adjacent, that figure still has Outwit.

No, just the one that gains Outwit.

And that is literally 'gains Outwit,' as in they have the power and it can be Outwitted, as opposed to a regular team ability that acts like a power (Batman team - Stealth, Skrull - Shape Shift) which cannot be Outwitted.

Well..... you have to be careful there. The team ability cannot be Outwitted, but the power itself can be. So say for instance that Brainiac is standing next to an Intergang figure. He has Outwit. Well, assuming he didn't already. If you Outwit Braniac's Outwit, then he can fly over to Doomsday. As long as Doomsday's point value is higher than Brainiac's, Doomsday still gets Outwit, as the team abilities are still there.

Good clarification. Didn't notice the vagueness in my original post. Insert a parenthetical

(the Outwit gained from the Superman Enemy team ability, not the ability to gain Outwit)

after the word "it" in my reply.

I didnt know this team ability was so confusing.