Smash Attack (move)
From the Super Mario Wiki
A Smash Attack is a special technique used by every character in all Super Smash Bros. games. When the player tilts the Control Stick very quickly and presses the A Button at the same time, they will use a very powerful attack that can cause massive damage to their opponents, and usually launches them. Starting in Super Smash Bros. Melee onwards, if the player holds the A Button, they will charge up the attack, making the Smash Attack even more powerful. In Super Smash Bros. Brawl, there is an option to do a "Shake Smash" with the Wii Remote and Nunchuk, which by shaking the Wii Remote, the character will perform a quick, uncharged Smash Attack on an opponent.
In Super Smash Bros. Brawl, due to the four types of controller options, some controllers won't support the same control method used in the last two games, but rather, use a different control method. Also, in Super Smash Bros Brawl, some enemies can use smash attacks too.