Episode 156
On their way to the Battle Pike, Ash and friends decide to ride along Cycling Road. However it is closed and they must go through the forest below. After hearing a noise, Pikachu wanders away and finds an injured Celebi under some thick vines. Ash and the others then meet up with the Pokémon Ranger Solana who agrees to help them find Pikachu. When they finally find Pikachu and Celebi, the reunion is short-lived as Team Rocket attacks wanting Celebi for themselves!
Aired 08/12/2005EP 156 - Episode 156
Pokémon the Series: Ruby and Sapphire
After participating in the Johto League, Ash decides to begin anew in yet another journey; this time by himself and Pikachu, in the land of Hoenn. Though he isn't alone for long, as 10-year-old May (who dislikes Pokemon, but just wants to come along to see the world) travels with him after Pikachu destroys her bicycle. Ash also meets up with his old companion, Brock, and May's younger brother, Max. Together, they travel along in Hoenn, battling Gym Leaders, entering Contests, and other events on the way to the Hoenn League.
(Source: Anime News Network)