S1·E4 Challenge of the Samurai

Misty and Ash continue to wander the Viridian Forest when they spot a Weedle. As Ash battles it, he's distracted by a boy dressed as a samurai and calling himself (naturally) Samurai. Samurai challenges Ash to a battle, and Ash gets the advantage when his Metapod defends itself against Samurai's Pinsir. Samurai sends out his own Metapod—and a standoff begins.