Pokemon Season 4 - Episode 187 – Moving Pictures

A chunk of ice falls from the sky. Our heroes examine the block and discover that a Sunkern is frozen inside. They get help from an elderly couple who are quick to lend a hand in thawing the Pokémon. Ash used the Sun Stone which he got from the Bug Catching Contest on Sunkern to a Sunflora. When it evolves, it brought all the Sunflora to happiness.