JE020: Chikorita's Big Upset

Synopsis
On their way to Azalea Town Ash has a battle with a local trainer in a new town. During the battle Ash recalls Chikorita for Pikachu but Chikorita refuses. The battle was called off on account of it getting late. At the Pokémon Center Ash wonders why Chikorita didn't want to be recalled, and after a thorough psychological analysis, the Nurse Joy reveals that Chikorita is jealous of Pikachu because Chikorita thinks Ash likes Pikachu more than her. Later that night Chikorita runs away and joins a gang of fighting-type Pokémon. Will Ash ever see Chikorita again? And will Chikorita get over its jealousy?

Trvia

 * This is another episode that reveals another Pokémon's gender, in this case, Ash's Chikorita is revealed to be female.
 * Ash battles a School Kid from Gen II in the beginning of this episode.
 * This is another episode where a Nurse Joy wears a different outfit.