Pokémon Season 4 Episode 33

On their way to Olivine City, our heroes pass through a dangerous looking canyon full of unstable boulders. When the rocks begin to give way in an avalanche-like fury, a few fiery Pokémon rush to the rescue. Once out of harm's way, Ash, Misty and Brock find they've been rescued by Ramona, her brother Kegan and their three Arcanine.