After separating from Ash and Misty, Brock returns home to Pewter City. When he arrives at the Gym, he finds out that it has been totally redecorated and turned into a water gym! He asks his siblings about it and it turns out that it was his mother. Brock convinces his father to battle for the gym but he loses to their mother. Then, Brock decides to take on his mother, with the future of the gym on the line!