Akuma
Known as Gouki in Japan, Akuma is the brother of Ken and Ryu's sensei, and was rumored to have killed Gouken, though he is very much alive in SFIV. Even if not guilty of fratricide, he definitely killed his master after discovering the dark powers that fuel him, and wears his late master's prayer beads around his neck. Akuma is one of the top bad guys in the SF universe, and was big in the Alpha sub-series. He's normally cast as Ryu's main enemy, pushing him on a darker path. Perennial loser Dan also sees Akuma as a rival, while Akuma just ignores him.
Amingo
One of the few original characters in MvC2, Amingo is a bit of a mystery. A sort of living plant, his standard look is that of a fat cactus wearing a sombrero and gaucho pants. This Hispanic homage is only temporary though, as he shifts into many different plant-like forms during a fight. His goals involve saving his plant brothers, but since MvC2 is one of the few Capcom fighters not to have character specific endings, we don't really know anymore.
Anakaris
Anarkis was a Pharaoh who foretold his own death and subsequent resurrection 5000 years later, so he had a pyramid prepared. Once brought back by the powers of Darkstalkers baddie Pyron, he begins fighting to save his kingdom. Once he does, he basically bounces around from the present to five millennia previous to defend his land, which he eventually saved by taking it to a new dimension.
B. B. Hood
Don't be fooled by her adorable looks - Baby Bonnie is one of the most dangerous people alive. In her world where monsters are real, hunting them for bounty or treasure is a dangerous but rewarding job that she is the best at. Hiding an armory of weapons in her picnic basket, she's a very proactive monster hunter. Even when visiting Grandma she is never without her beloved Uzi and her equally beloved dog Harry.
Blackheart
Part of Marvel's crown demon family, Blackheart is the son of Mephisto, the universe's equivalent to Lucifer. Created to help destroy the virtuous, Blackheart rebelled and even overthrew his dad occasionally, but Mephisto always comes back. He's been in charge of his own portion of Hell and has gone after Ghost Rider from time to time. He's also one of the most powerful beings in the Marvel U, with virtually limitless power and invulnerability (except to Hadoukens).
Cable
Cables backstory is nearly indecipherable to casual fans, and it all starts with him being Cyclop's son from a possible future that comes back to the present to prevent the future hes from. Though he possesses telekinetic and telepathic powers, they are almost always committed to containing the techno-organic virus that has turned an eye, arm and leg into robotic accessories. He makes up for that with his love of guns and explosives, including his extremely cheap air grenade. Most famous as leader of the X-Force, and was instrumental in ending Apocalypse's plans for controlling the world. These days Cable is often seen with the mutant mercenary, Deadpool.
Cammy
Cammy has a complicated past. Created as a clone and having the DNA of evil Mastermind M. Bison, she was a brainwashed assassin for Bison's crime organization Shadaloo. Eventually she broke free of it, losing her memory and joining Britain's MI-6 intelligence group, which appreciated her killer abilities. No longer ashamed of her past, she's recommitted her group of agents to taking down evil worldwide. And she does it all from a confusingly revealing leotard, which is apparently standard MI-6 attire.
Captain America
A patriotic but sickly kid, Steve Rogers wanted to serve his country in WWII. He was given an experimental serum that made him a super soldier, a man at the peak of physical perfection. Pretty soon he and his indestructible shield were punching Hitler regularly. At the war's end he was frozen and awoken in modern times consistently leading Marvel's premier team, the Avengers. Currently he's dead, struck down by his nemesis the Red Skull, but we'll see how long that lasts.
Captain Commando
One of Capcom's first mascots, Commando showed up on the manuals and boxes of early Capcom games, with his name made up of his company's - Cap. Commando. Eventually he got his own brawler, taking place in the now not so distant future of 2026. With the help of his Commandoes he cleans up Metro City of the future. With his fancy armor and special attacks it gives him, Commando made the world of the tomorrow a safer place, but in the present he's no longer Capcom's mascot, but does appear from time to time.
