Primeape Goes Bananas

On their way to Celadon City, our heroes encounter Mankey, a wild Pokémon that, if rubbed the wrong way, can go into uncontrollable fits. Not realizing this, Ash tries to capture it, but accidentally upsets it. To make matters worse, Team Rocket shows up and agitates Mankey further, causing it to evolve into Primeape, who then attacks the heroes. Eventually, Ash and Pikachu tame the savage beast, and Ash captures it.