From the Super Mario Wiki
Clay Shooting is Duck Hunt's side special move in Super Smash Bros. for Nintendo 3DS / Wii U, based upon the clay shooting mode in Duck Hunt. The dog throws a clay pigeon that flies across the screen, exploding when the player presses the special attack button a second time to shoot it, the Zapper firing three shots that also deal damage. The pigeon only explodes once the player presses the button, though it still damages opponents.
This move also has two custom variants that can be unlocked. The first one is Rising Clay, which causes the pigeon to arc downward and then fly up when tossed; however, the pigeon does not explode, meaning that it deals less damage. The second is Clay Break, which tosses the clay farther and at a higher arc but it the pigeon itself does not damage opponents and the shots are more spaced when detonating, though are more powerful.
Super Smash Bros. for Wii U trophy information