"Herculean Task" achievement hint
First, set the game to the Very Hard difficulty setting, 30 second time limit, and damage on highest. Select Task Master with Aim Master Assist, Chris with Gunshot Assist and Dr Doom with Plasma Beam Assist. Then, keep using the projectiles from the corner to win every match. When you reach Galactus, activate X-Factor and do a Hyper Crossover Combo to take out a decent amount of health. He will hit you before you finish. At this point, fight him as you usually would.