Pokeman - The Movie 2000

Ash returns all three treasures to the central isle, causing a green liquid to pour out into the stone basin.

Melody follows the prophecy and plays the song of the guardian Lugia. The legend comes to life as Ash and the four legendary birds Lugia, Articuno, Zapdos, and Moltres fly together to calm the churning underwater current that would have destroyed the world otherwise.

Before returning to the sea, Lugia informs Ash that he made all the difference in the world.

Professor Oak and Ash's mother catch up with everyone. Ash's mom tells him that she has so much trouble as his mother to not worry about him while he is on his pokemon adventure, and can't help missing him all the time, but she understands that it is the life he wants, and reminds him that he's always her hero.

Team Rocket contemplates the situation of how they helped save the world, but still didn't catch Pikachu.

Thanks Herbmeistr!