Official Roster

Here's the official roster and their hero options:
Surefooted Sentry - Spider-Man (pick one variant; excludes EOTE and Ultimate Comics Spider-Man) or Bombastic Bag-Man
Glittering Giraffe Pudding - American Dream, Captain America (pick one variant), or Bucky Cap
Lieutenant Ghost Avenger - Monkey King or Beast
Space Hawk - War Machine, Dark Iron Patriot, or Iron Patriot
Adventuring Invincible Saber - Black Widow (excludes Avengers Black Widow) or Psylocke
Dare Catching Librarian - Nightcrawler or Gambit
The Punishing Lawyer - Ms. Marvel, Falcon, Cyclops (pick one variant), or Thing (pick one variant)
Enraged Shield Hunter - Hawkeye (pick one variant) or Nick Fury (pick one variant)
Astounding Super Bird - Mr. Fantastic, Quicksilver, or Shadowcat
Wailing Crusader Gargoyle - Firestar, Mohawk Storm, Daredevil (pick one variant), or Sentry
Plastic Fantastic Fungus - Venom or Green Goblin
Omega Librarian Gardener - Werewolf or Squirrel Girl
Marshmallow Hydra - Storm or Rogue (pick one variant)
Kingdom Sloth Crusader - Cable or Hope Summers
Toxic Iron Cat - Human Torch or Iceman
Captain Fighter Warrior - Iron Man (pick one variant; excludes Stealth Armor Iron Man) or Rescue
Smashing Clown Juggler - Havok or Nova
General Warlike Smasher Hammer - Thor (pick one variant) or Valkyrie
Invisible Martian Archer - Hulk (pick one variant; excludes Red Hulk and Indestructible Hulk) or She-Hulk (excludes Red She-Hulk)
Masked Frost Builder - Dr. Strange or Captain Marvel
Ice Prince Sun - Wonder Man or Guardian
Volcanic Torch Manatee - Moon Knight or Blade
Steel Autumn Machine - Arachne, Spider-Woman, Spider-Girl, or Black Cat
Storm Builder - Magneto or Doctor Doom