I've been obsessed lately with getting all the Ultimate Marvel Heroclix and thought this was a super awesome scenario...and also really simple to boot...

Nick Fury has allied with the Fantastic Four's greatest foes, Namor and Doom, to take them out because they've turned against SHIELD...

Ultimate Nick Fury - 63
Ultimate Namor - 151
Ultimate Doom - 186
= 400

versus...

Ultimate Vet Mr. Fantastic
Ultimate Vet Invisible Woman
Ultimate Vet The Thing
Ultimate Vet Human Torch
Brilliant Tactician
Unstoppable
Fantastic 4 ATA
= 400

The scenario is pretty simple. I am thinking it'd be at the Baxter Building Map with no BFCs in play and no theme bonuses (because the Fantastic Four are good enough as is).
I also think Fury's team would go first.

The teams are pretty even. Fantastic Four ATA isn't too dirty because I always felt the Ultimate F4 Villains could take down the F4 conceivably with their awesome attack stats and good power combos. Like Doom has good attack with Pulse Wave which means the ATA doesn't do anything. Namor always has good attack. Fury is great for the points plus adds SHIELD TA to himself and Doom. But ofcourse everyone knows how awesome the F4 is with the ATA and Brilliant Tactician.

It just looks like A LOT of fun to play no matter which side I got stuck on and could play out great matches over and over.

1 cool thing to decide is if you want to do it until death or by points because there's arch rivals on the board. Another option is if you want to add Franklin Storm pog to the F4 and be a little more theme accuracte while giving up Unstoppable or Brilliant Tactician.

Looks cool.
You probably could get better results if you traded out a few figures for more efficient versions, but for pure for-fun play this looks excellent.

What versions would those be?

Well, it's hard to get more effective on a Fantastic Four team than LE Sue Storm. Especially if you play the Fantastic four ATA, which you do.
I think LE Reed Richards gives slightly better value for your points than V Mr Fantastic - that Enhancement is hard to use. The Experienced version is also a good way to save points - odds are you won't end up on click 2 anyway.
When it comes to Human Torch and Thing the Veterans are definitely the best versions though - unless you are going to use the Starter set Thing, but that's not the theme you are going for, so I'll only mention it in passing.

To be honest the Veteran is my favourite because Enhancement is one of my favourite powers ever. I love a lot of IC stuff and Nightmare and Dr. Strange are two musts for me because of that power.
The reason Sue Storm wasn't chosen is because I didn't want to tip the scales too much. The F4 already has 3 effective pieces of cardboard on their side while their opponents have nothing going for them but being consistent with powers and numbers and worth the points.
I will consider your choices if I ever feel like making a more competitive Fantastic Four to play outside of scenario. I am still deciding if I'll want to get the LE versions of them.

I have them all, but I only see reason to hang on to Reed Richards (FF, not SI) and Sue Storm.

Ben Grimm goes down to 0 damage? That really is pathetic.
The 2nd LE Johnny Storm's sculpt makes him worth getting.
The cost of the regular LE Johnny I understand about as much as Ben's...why are they so bad?

The reason I'd get them is I like to match....Vets with Vets...LEs with LEs....Ultimates with Ultimates...that whole deal...

I think that is an error in the Units section. Unfortunately I cannot check my own figure right now.
Yeah, that's a good point - I haven't gotten that one as mailaways are hard to get when you don't live in the US, and he didn't seem worth the effort to me. But the sculpt and the fact that he is the only Human Torch (that I know of) with 10 range and dual targets does give him a niche to fill.
No idea. I pulled both as Super Rares (got like 3 Super Rares from half a case of FF, and only 2 Uniques - both Mad Thinkers...), otherwise I wouldn't have bothered getting them.
Yeah, it's always nice to see a team where the ring colors all match.