Ep. 77: Evolution by Fire!

77

Stopping at Abtilbe Town's Battle Club, Ash meets his Tepig's former trainer, Shamus, who abandoned Tepig because he felt he was too weak. Angry, Ash challenges Shamus to a double battle with Snivy and Tepig going up against Shamus's Emboar and Heatmor, during which Snivy takes a hit to save Tepig, which motivates him to evolve into Pignite. (Source: Wikipedia)