Silver surfer (Yes, it’s alright to cheat for him. It’s like impossible otherwise).
Dr. strange (Black magic/mind wipe rule).
Wolverine (Once he’s raged, used spin attack. Everytime he spun he whammed doom).
Luke cage (Unless your playing easy. You need a guy who is simply near impossible to die. Otherwise…)
Captain America is an excellent choice. Shield throw is arguably the best power in the game.

Here’s my scoop on others.

Elektra-no. I really don’t like her.
Thor, Mr. Fantastic, Deadpool: These guys are all great hybrids, and, they all have super xtreme attacks. Yes, in case you are wondering, not all xtremes are equal.

Human torch is really good. Personal favorite ability is when he uses fire to pop right underneath enemies. This works on shielded ones as well. Once on ground, pound away.

Spider man: First 2 abilities and last ability are great. All offensive abilities in between are quite poor. Web shield is an ability i give highest possible reccomendation. Maxed out, it blocks 70% (Not kidding!) of damage. Even on bosses.

Nick Fury: Really fun to play. Use SMG and SNIPER abilities. Smg is when he pulls a gun out and fires, but he can still move while doing so. Sniper is a great ranged and i believe about 25% chance of instant death.

Thing: Great subsitute for Luke Cage. Just go by personall preferences.

That’s pretty much all that comes to mind. Hey!!! there are a lot of characters in MUA. I’ll continue the guide. Looking forward to MUA II!