Winter Soldier
Abilities: Bucky Barnes received a variation of the Super Soldier Serum, which gave Captain America his abilities. He has enhanced strength, durability, speed, agility, reflexes, and healing. He also has a cybernetic arm, now made of Vibranium, which increases his strength even more.
Power scale: 4. We've seen Winter Soldier hold his own against Captain America, Black Widow, and expertly assassinate scores of people — but all while being mind controlled by Hydra forces, which made him cutthroat and ruthless. Ever since Shuri was able to "reset" his mind, we've only seen him use a gun. It seems he's not as effective as he once was. On top of that, thanks to "Civil War," we know his arm can be forcibly removed or blasted off, which makes him vulnerable in a battle against super-powered people.