When Nobita feels like diving in his hometown, Doraemon uses a Underwater Pump Simulator to pump all the water out of Tokyo, causing the entire city to go underwater. That night, Doraemon and Nobita use a Diving Mask Simulator to dive underwater. Later on, lots of fish, and a shark attack Doraemon and Nobita. So, Doraemon puts a stop on the Underwater Pump Simulator, but there is a girl named Sophia, lying down on the bushes in his neighborhood.

40 years ago, a Celebi was being attacked by a Pokemon Hunter. Luckily, a young boy named Sammy saved Celebi. Using its Time Traveling power, Celebi transported himself and Sammy 40 years into the future. There, Ash, Misty, and Brock assist Sammy to the healing lake in the forest so they can heal the wounded Celebi. Unfortunately an evil Team Rocket member, Viscious a.k.a. "The Iron Masked Marauder", tries to capture Celebi using his technology. As Ash and Co. try to get away from Viscious, they also run into Jessie, James, and Meowth, who also want to capture Celebi. Soon it becomes a race against time to get Celebi and Sammy back to the forest before Celebi is caught and is used to destroy the forest and themselves.

After a scientific experiment leads to the creation of Mewtwo, he sets out to destroy the world. Satoshi and his friends then decide to thwart Mewtwo's evil plans.

Satoshi must put his skill to the test when he attempts to save the world from destruction. The Greedy Pokemon collector Gelardan throws the universe into chaos after disrupting the balance of nature by capturing one of the Pokemon birds that rule the elements of fire, lightning and ice. Will Satoshi have what it takes to save the world?