Dodgeball has two fundamental rules: hit the other team with the ball and don't get hit yourself. Besides moving out of the way, another way to prevent yourself from getting hit is to catch or counter an opponent's throw.
Some characters have special catches or counters unique to themselves while others have a standard method. The standard way to counter a thrown ball is to press B/Circle button or the Z/J key with the correct timing before the ball hits you.
Characters such as Otto and Balloony will catch the ball and allow you to throw it back or pass it to another teammate. Characters like Mina and Suneko will counter and immediately send the ball back at the other team. There are also characters with different input methods. Suneko is one of these. Her counter requires you to hold the button and then release it once the ball is close rather than just pressing the button.
Catching and countering is a very important aspect of Dodgeball Academia's combat as it prevents you from taking damage. It also allows you to prevent the ball from bouncing off your face and back onto the other team's side.