Duck Hunt is a trio character consisting of the dog and a duck from the namesake game, as well as an unseen gunner. The duck rides on top of the dog's back to help him out in battle, while the gunner assists the duo by shooting with the Zapper, an NES accessory, for their Smashes as well as some of their Specials.
The dog didn't do much in the Duck Hunt game besides picking up ducks the player shot and laughing at the player when he or she missed shooting them. But thanks to its duck partner, some attacks derived from Wild Gunman and Hogan's Alley, and assistance from the unseen gunner, this dog's pretty much good to go. Of course, the dog will laugh at you on multiple occasions.
Text by Professor Squeaky & Smashedpotatoes