Pokémon S15 E29 Evolution by Fire!

"Gotta catch 'em all!"

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.