We play 400 pt, must use 2 starter figs, all figs must have Avengers keyword since I am an Avengers team, and golden age.

I'm thinking:
AVX Scarlet Witch 100 (Emma fragment)
AVX Wolverine 75
AVX Black Panther 100 (Namor fragment)
ASM Spider-man (201) (Cyclops fragment)
Colossus Fragment on dial to tap the invulnerability.

Strategy:
BP and SM copy SW's mystics.
Wolverine acts as a draw but possibly healer if needed.
SW stays within 4 of BP so she can use No More Mutants without taking her off her top click. (Also, when side-step comes in, he can move back in for some support.)
SM's ranged power knocks three off of opponents attack even if his 2 damage doesn't get through, so Wolvie doesn't need to take such a bashing.
BP's leadership keeps tokens off Spidey or trait gives SM willpower when he needs it.

Not going for powerhouse-type team. Just want to have fun game. But without a lot of time to play test, what kinds of flaws do you see or things do I need to look out for?

Thanks.

Biggest thing that jumps out at me is 4 non-fliers.

Agreed 100%. You have a very well thought-out team, minus mobility. Spidey obviously can get around using his Improved Movement, but the others may struggle a bit to keep up.

Hmm. At 400pts with a min of two Starter Set pieces, you're extremely limited. You want to get the most of your pieces for that price and I don't think your team gives you that...

Something like this may give you some more versatility for your restrictions:

125 AVX004 Spider-Man
100 AVX002E Iron Man
75 FFCW006 Scarlet Witch
72 HA040 Captain America
27 IC085 Black Panther

= 399pts

I would play test more. Much more testing with a certain cool guy I know.