Pokémon : S3 | E4 – Roll On, Pokémon!

Ash and his friends come across a scenic valley, which they must pass in order to reach Violet City. As they continue onward, the ground starts to shake and some large rocks fall from the cliff above. Meanwhile, Team Rocket is sitting by the ledge on the same cliff. When more tremors hit, the rock they are sitting on crumbles beneath them, and the trio falls into the forest below, with tree vines helping to break their fall. Ash, Misty, and Brock continue along a dirt trail, when they stumble upon a Donphan amongst the shrubs. Ash is about to catch it when Brock stops him, saying that it must be young due to the short size of its tusks. Brock then suggests catching Donphan because it needs a Pokémon Breeder. Ash and Brock then start arguing over who would be the best Trainer for Donphan, only for Misty to cut in and tell them that Donphan is walking away.

At this, Brock calls out Onix and commands it to use Tackle on Donphan, sending it backward. However, Donphan soon recovers by curling up into a ball and rolling at Onix, hitting and defeating it. Ash then sends out his new Heracross, who uses Tackle, sending Donphan flying backward. Donphan jumps back up and charges forward with another attack. Heracross uses Horn Attack, which hurtles Donphan into a tree trunk. As Ash is about to order his finishing attack, a girl intervenes. She checks on Donphan's health, then threatens to turn Ash in to Officer Jenny for attempting to steal her Pokémon. Ash apologizes for the misunderstanding and explains that he and Brock thought that Donphan was a wild Pokémon. At that moment, Brock starts flirting with the girl, who identifies herself as Rochelle. Disapproving of Brock's advances, she pulls away as Brock comments on her amberite necklace. Rochelle informs the group that all of the Donphan are hers, and Ash agrees to desist from trying to catch any of them. After denying Ash's request for a battle, Rochelle walks into the trees and disappears.
(Source: Bulbapedia)