Evolution by Fire!

On their way to Iccirus City, Ash & Co. bump into a trainer who maintains he has the strongest Pokémon. It turns out that this trainer is the original trainer of Ash's Tepig, who discarded Tepig, thinking it was weak and not worth training. Ash gets angered by this attitude and decides to challenge him using Tepig in a Double Battle to prove him wrong. Will Tepig be able to show his previous trainer how strong it is, or will that trainer turn out to be right?