Here is the full list of all 30 Marvel vs. Capcom Origins achievements worth 400 gamerscore.
Complete the second tier of the challenge “Looking Cross"
Complete the second tier of the challenge “Aerial Rave"
Finish arcade mode without losing a round (Marvel Super Heroes)
Complete the third tier of the challenge “Powers Combined" (Marvel vs. Capcom)
Complete the fourth tier of the challenge “Big Finish”
Complete the third tier of the challenge “It's Not Over"
Complete the third tier of the challenge “Duo of Heroes" (Marvel vs. Capcom)
Win a match with every character (Marvel vs. Capcom)
Finish arcade mode (Marvel vs. Capcom)
Complete the third tier of the challenge “Your Turn" (Marvel vs. Capcom)
Complete the third tier of the challenge “Hyper Artist"
Complete the second tier of the challenge “Heroic Banter"
Complete the third tier of the challenge “Hip Tosser"
Complete the second tier of the challenge “Level Up"
Finish arcade mode with each hero (Marvel Super Heroes)
Complete the third tier of the challenge “Another Notch”
Complete the first tier of the challenge “Uatu the Watcher"
Complete the second tier of the challenge “Not a Scratch"
Finish arcade mode with each villain (Marvel Super Heroes)
Complete the third tier of the challenge “War of the Gems" (Marvel Super Heroes)
Complete the third tier of the challenge “Going Streaking"
Win a match with every normally selectable character (Marvel Super Heroes)
Finish arcade mode (Marvel Super Heroes)
Complete the second tier of the challenge “Chain Reaction"
Complete the second tier of the challenge “Fast Fingers"
Finish arcade mode without losing a round (Marvel vs. Capcom)
Finish arcade mode with each Capcom character (Marvel vs. Capcom)
Finish arcade mode with each Marvel character (Marvel vs. Capcom)
Finish arcade mode with each Hidden character (Marvel vs. Capcom)
Complete the third tier of the challenge “Grinder"