Captain America first appears in the second skit of the Marvel Ultimate Alliance 2/Captain America: Super Soldier Gameplay video. He is hiding on the stairs while Iron Man is asking him if he is going to register. Captain America then asks him for what he is going to register before running away from the stairs, Iron Man pursues him and finds him holding a poop hound in the air and a poop hound head. He throws a piece of snow at Captain America who in return throws the poop hound head at Iron Man and hides again for a bit before pursuing a crawling Iron Man and beating him with a shield, the clip then cuts out.
We later see him in the third skit, where he hides from Iron Man in a closet. Iron Man opens the closet and hits him with an umbrella multiple times before fleeing to the backyard. Captain America chases him with a poop hound once again and picks up snow with it and throws it at Iron Man. Captain America continues to do this until he runs into a fence and falls, hurting his back on some tree branches.
Captain America's second and last appearance is in IRON MAN VS CAPTAIN AMERICA. He wakes up in the morning and walks to the fridge where he takes a beer and a shopping list attached to the fridge with him. He then enters his car and drives to a Super Market, while there his cart bumps into Iron Man's and they share a small chat together. Iron Man asks Captain America if he is going to register and Captain America says that he is going to think about it. Captain America quickly leaves and we next see him putting his groceries in his car trunk, Iron Man appears and asks Captain America once again if he is going to register, Captain America once again says he is going to think about it since he doesn't really agree with the view. Iron Man then insults Captain America and steals his eggs.
Captain America then drives to a gas station and sees Iron Man again, he shows the superhero registration documents at Captain America before driving away. Captain America then strives home and enters through the garage door, suddenly Iron Man enters through the door too and asks Captain America for the last time if he is going to register, Captain America says no and a fight ensues. Iron Man repeatedly throws the stolen eggs at Captain America until he takes out a dog deodorant from his grocery bag and sprays Iron Man in the face. Iron Man screams and falls to the ground before being quickly picked up by Captain America, he punches Iron Man twice and throws him at nearby cardboard boxes. Iron Man then reveals that he has an illness and is going to die soon, due to this Captain America agrees to sign the registration act, and does so while Iron Man repeatedly throws eggs. After he is done signing, he throws the documents at Iron Man along with some cardboard and leaves the garage.