From the Super Mario Wiki, the Mario encyclopedia
Hyper Rocketbarrel is Diddy Kong's new Final Smash in Super Smash Bros. Ultimate, replacing Rocketbarrel Barrage from previous games. When it is used, Diddy Kong activates his Rocketbarrel Pack, flying at a high speed in several directions, dealing damage to any opponent upon contact. After a certain period of time, Diddy Kong locks onto his opponent; in the case of battles with more than two fighters, Diddy Kong homes in on the fighter that has taken the most damage. The final hit of Hyper Rocketbarrel launches opponents.