Still going with the old Arc Reactor - Chrono Overdrive - Fault Eater - Phoenix Flame.
AR-CO-PF is the one shot kill that I am going for in round two. It's not as strong as it used to be when I could use it in round one, but is still powerful enough.
The Fault Eater is very interesting. It does very little damage but DOTs for 2k, so unless the opposing team is immune to either poison/fire or has heroes that eliminates them, it's a very stable source of damage. Also it does not trigger counter or protect abilities, which allows my agent to attack without having to meet Captain America. Not only that, it seems to have a very good chance of getting past Emma's diamond body and deals decent damage when used in conjunction with AR-CO, making it a decent finisher or pick-off weapon.
I will be using this until I get enough CPs to get WW2 Captain America and have him level up past 10, but so far this setup works well with...
P5 Emma and FF Invisible Woman.
Emma is yet another way of bypassing Captain America since her attacks other than War Diamond cannot be protected or countered. Her War Diamond also gets rid of debuffs much the same way as Unlock Potential with the exception of Mental Anguish, and her Cosmic buff eliminates many debuffs randomly while granting a stat boost. Of course unlocking potential just before AR-CO-PF allows for massive damage, and since PF cannot be used in the first turn, you are guaranteed a chance to unlock potential your agent.
Her diamond body provides good protection and her lvl 9 attack also serves as a protective move since migraine does decrease damage by quite a bit. War Diamond stuns quite often and is a great way of knocking out the opposing agent, provided that he is not protected by Captain America.
FF Invisible Woman was also chosen for her ability to bypass Captain America and because she is the perfect counter for AI Captain America. AI Captain America will, almost without fail, use the shield throw after shield guard, so IW will always counter with her powerful lvl 1 attack unless CA happens to be a bruiser.
Her force field is very good at dealing with Mocking Bird, as is her force cage. Her force cage, in conjunction with the Flame Eater, is an easy way to nibble at the opposing team's hp provided that they don't have Emma who can lift the cage using Unlock potential (as well as the other debuffs).
The only thing is that she's quite vulnerable to Magnetic fields (as is the Phoenix flame). That's where psychic attacks come in handy and hence why I used to have Phoenix, but the Phoenix does not have the versatility of IW.
Oh, and the fourth field from her FF suit also helps out quite a bit.
It's not the perfect setup, and I would put Mocking Bird without a second's hesitation and change my setup accordingly, but unfortunately I started the game a bit too late...