Defensive Power Shot
From the Super Mario Wiki
Defensive Power Shots are a type of Power Shot used by the characters in Mario Power Tennis. It is used to return the tennis ball from wherever it is to back to the other side of the court. Defensive Power Shots are also capable of negating the added effects of Offensive Power Shots. A player can activate a Defensive Power Shot by holding and pressing while having a glowing racket. The button can be used instead of the and buttons. If a character attempts an Offensive Power Shot, but they are too far away, a Defensive Power shot will be utilized instead. Some characters, namely Mario, Princess Daisy, and Petey Piranha, may not return the ball if they are too far away, even though the Defensive Power Shot is performed.
The returns of the Defensive Power Shots can vary, such as Peach's lobbing the ball or Petey Piranha's drop-shot.