You’ll receive a chest, money, experience, glory points, union points, and Sunshine Medals for winning battles. The size of the reward depends on your contribution to the victory and your place in the ranking.
Try to win before the timer runs out or else the game will end in a draw, and there’ll be no winner. If you don’t win in time, don’t despair: you still get a consolation prize for all the damage you dealt.
Still, if you score less than 51 points, you won't get even the consolation reward.
You can get a beach hat as a prize, if you land the last hit on an opponent during a fight. Beach hats are exchanged for perfect items from Exclusive tab in the shop.