JE104: The Mystery is History

Synopsis
On an island near Silver Rock Isle, Ash and co are reunited with their old friend Ritchie, who they haven't seen since the Indigo League. After they catch up, Ritchie tells them he's been on the lookout for the Mystery Pokemon of the Whirl Islands. They soon encounter a young boy named Oliver who was playing with an unusual Pokemon, a Lugia. However, it was much smaller and Oliver nicknamed it Silver. Eventually they meet their old friend Luka, who takes them deep sea diving and find the child's parent. But are they the only ones interested in Lugia?

Debuts
Pokémon
 * Pupitar
 * Lanturn
 * Lugia

Trivia

 * This episode is also part 11 of the 13 part Whirl Islands arc.