"Pokémon 4Ever" is the fourth movie in the Pokémon anime franchise, set within the continuity of the main series. The story begins with a young boy named Sam, who lives in a forest 40 years in the past. After encountering the legendary Pokémon Celebi, Sam is pursued by a Pokémon hunter who seeks to capture Celebi for its time-traveling abilities. In a desperate attempt to escape, Celebi transports both Sam and itself to the present day, where they encounter Ash, Pikachu, and their friends.

Ash and his companions befriend Sam, who is unaware of the time shift, and together they work to protect Celebi from the hunter, who has also followed them to the present. The hunter, now allied with the villainous Team Rocket, uses a Dark Ball to corrupt Celebi, turning it into a destructive force. The corrupted Celebi begins to wreak havoc on the forest, endangering both Pokémon and humans.

As the situation escalates, another legendary Pokémon, Suicune, appears to aid Ash and his friends in calming Celebi. With the help of Sam and the forest's Pokémon, Ash manages to free Celebi from the Dark Ball's influence. However, the ordeal takes a toll on Celebi, and it appears to perish. In a poignant moment, Celebi is revived by the collective energy of the forest's Pokémon, demonstrating the deep connection between nature and Pokémon.

The story concludes with Celebi returning Sam to his own time, ensuring the preservation of the timeline. The film explores themes of friendship, environmental harmony, and the consequences of human greed, all while maintaining the adventurous spirit of the Pokémon series. The main characters, including Ash, Pikachu, and Sam, are central to the narrative, with Celebi serving as both a catalyst for the plot and a symbol of the natural world's resilience.