An up smash (abbreviated u-smash) (上スマッシュ攻撃, Up/upper/above smash attack) is a smash attack performed by any character by tapping the control stick upward and pressing A, or, outside of Melee's single player modes, by pressing up on the C-Stick.
Since Super Smash Bros. Melee, all smash attacks can be charged by holding down the A button for up to one second, multiplying damage and knockback by up to 1.4. In Ultimate, these charges can be held for up to 3 seconds (or 180 frames), but the attack stops increasing in strength after the 1-second mark.
Up smashes have more flexibility than forward smashes and down smashes in terms of when they can be used. A jump may be canceled into an up smash, enabling it to be used out of shield immediately and during any part of a character's dash animation, except the skidding animation when they stop running. From Brawl onwards, jump-canceling to perform a running up smash is unnecessary, and the turn-around animation can be jump-canceled into a reversed up smash. In Ultimate, jump-canceling is not required for up smashes out of shield, and can now be done instantly.
List of up smashes
Notable up smashes