Pokémon (1997)

S15E29 Evolution by Fire!

While visiting the Battle Club in Abtilbe Town, Ash encounters Shamus, Tepig's previous trainer, who had cast Tepig aside, believing him to be too weak. Furious at Shamus's actions, Ash proposes a double battle, pitting his Tepig and Snivy against Shamus's Emboar and Heatmor.