Marvel Vs. Capcom 2 (thing)

There are 56 characters in Marvel vs. Capcom 2 28 from Capcom games and 28 from the Marvel Uninverse

Capcom

From the street Street Fighter series

Akuma/Gouki(JP)
Cammy
Charlie
Chun-Li
Dan
Dhalsim
Guile
Ken
M. Bison/Vega(JP)
Ryu
Sakura
Zangief

Dark Stalkers/Vampire Savior(JP)

Anakaris
B.B Hood/Buletta(JP)
Felicia
Morrigan

Mega Man series

Mega Man
Roll
Servbot/Kobun(JP)
Tron Bonne

Misc.

Amingo from Buster Bros.
Hayato from Star Gladiator
Jin Saotome from Cyberbots
Jill from Resident Evil
Ruby Heart created by Capcom for this game.
Captain Commando title character from Captain Commando.
Son Son another title character.
Strider once again a title chacter.

Marvel

Characters from the X-Men series

Cable
Colossus
Cyclops
Gambit
Iceman
Juggernaut
Magneto
Marrow
Omega Red
Psylocke
Rogue
Sabretooth
Silver Samurai
Sentinel
Spiral
Storm
Wolverine with bone claws or with adamantium claws

Misc

Blackheart
Captain America
Dr. Doom
Hulk
Iron Man
Shuma-Gorath introduced in Marvel Premiere #6
Spider-Man duhh...
Venom also from Spider-Man
War Machine
Thanos