Offensive Power Shot
From the Super Mario Wiki
An Offensive Power Shot is a type of power shot used in Mario Power Tennis. It is used to give a shot some extra force when going to be received by the opponent making it harder to receive and in doing so affects the receiver in some way. For example, when Bowser's Offensive Power Shot is hit by any receivers, they are pushed back by the massive force of the flaming ball. Other Offensive Power Shots can also make the player move slow for a short amount of time. All players have their own Power Shot. However, these added effects are negated when the receivers use their Defensive Power Shot.