At the S.H.I.E.L.D. save zone select "Change Team" and delete all selected characters. To unlock Daredevil, press Left(2), Right(2), Up, Down, Up, Down, Start. To unlock Silver Surfer, press Down, Left(2), Up, Right, Up, Down, Left, Start.
To complete all the Comic missions easily and unlock Silver Surfer and get gold at the same time, wait and play all the missions at the end of the game when your characters have leveled up and have great powers. If some are still to difficult to complete, do some Versus mode missions with those characters to level them up, or to pick up some Shield Tokens to add to their costume.
To get easy experience and money in Mephisto's Realm, go to the part where you throw the Demon Jumpers into the fire to lower the pedestal, and stand by the edges of of the level where they respawn. Repeatedly kill them to gain experience and money.
When picking up character specific items such as "Iron Man's Coil", it is described as doing +3 Damage and +3 Rocket Uppercut. This is not +3 to damage for the hit; it means that it adds three dots in the Powers area. With this single item you can go from 129 Damage to 289 Damage.
Use Wolverine's Lunge attack as it normally knocks down the opponent and slashes them, but this does not happen with bosses. Continue to perform that attack and it will do more damage than melee attacks. When you run out of energy, the Boss should eventually produce some.
For a hard to kill team, make a team consisting of Wolverine, Blade, Ghost Rider, and Luke Cage (the Bad To the Bone team). The team bonus will be that 5% of all damage will regained as health. Also, all these characters have a way to regenerate health. Equip the following outfits: For Wolverine, Astonishing, Max Out Health Regen and Defense. For Blade, Ultimate, Max Out Health Regen and Defense. For Luke Cage, New Avengers, Max out Health Regen and Defense. For Ghost Rider, Original, Max out Resurrect Ally and Defense. It is also recommended that Ghost Rider be equipped with The Heart of Mephisto (10% of attack damage turned into health) or a similar item as he is the only character without a Health Regen. Equip other characters with gear that increases defense or evasion capabilities. Not only will your team be difficult to hurt, but they will be absorbing and regenerating most of the damage they take. If a teammate dies, Ghost Rider will have a 50% chance of resurrecting them. Note that Ghost Rider is the weak point since he does not regenerate and, if he dies, resurrection is lost. Also, Wolverine will regenerate the quickestbecause he has an inherit ability to regenerate in addition to the suit's bonus.
For easy money, health, energy, Extreme Momentum Orbs, and experience for leveling. make a team that includes Luke Cage, Elektra, and Dr. Strange. When they each have a full Momentum bar, get a group of enemies around you. Then, use the power. Elektra will stun all enemies with her Curse of the Hand. Then Dr. Strange uses his Mystic Maelstrom to kill all stunned enemies, causing them to drop Extreme Momentum Orbs for each enemy killed. Then, Luke Cage uses his Sweet Christmas to kill any of the remaining enemies, giving you +472% more money for each enemy killed in the attack sequence. This trick is especially useful for unlocking costumes, leveling characters, and maxing out stats. The best place to do this is in the Shield training simulator on the Thunderball mission. Even if you run out of time, you will still get the levels and money; do not worry about killing the Boss. Just get your momentum on Luke Cage, Dr. Strange, and Elektra.
When you get to the end of the mission to battle Ultimo, go back to the door you came in. Ultimo to big to pass the edge of the room he is in. You can just sit back and hit him with your ranged attacks. Then, fly in and collect the health and energy vials he drops.