When the new Avengers team was formed, she was invited to join. She had designed a costume, created disc weapons that looked like miniature versions of Captain America's shield, and underwent a lot of physical training to make herself as strong and as agile as humanly possible.
She joined the team as the "American Dream". Shannon soon proved herself to be worthy of Cap's colors, and when the team had to save the original Avengers from a dark parallel reality, she proved that she was worthy of his shield; The original Captain America gave her the alternate Captain's shield.
American Dream is in peak physical condition for a non-powered human, and is a skilled martial artist. She has disc weapons similar to those used by Ricochet and has terrific aim. Later she was given a duplicate of Captain America's shield (more accurately, the shield itself from another dimension), and she uses it well (both defensively and offensively).