Pokémon : S5 | E53 – You’re a Star, Larvitar!

Ash and his friends have reached the base of Mt. Silver and are nearing the Silver Conference, so they stop at a Pokémon Center to rest. The group also decides to call Professor Elm. The Professor admires how well Larvitar is developing, making a point of its gain in self-confidence. Elm gives Ash instructions as to what to do when the group reaches the top of the mountain, right before ending the call. Just then, a Trainer approaches them and makes the assumption that the group is on their way to the Silver Conference. The boy wastes no time in challenging Ash to a battle.

Just outside of the Center, the boy introduces himself as Satchel. Ash and Satchel take their places at opposite ends of a battlefield. Satchel sends out his Magby, prompting Ash to consult his Pokédex. Having learned that Magby is a Fire-type, Ash decides to send out Cyndaquil. Misty is surprised by his choice in Pokémon, wondering why Ash didn't choose his Totodile to battle Magby. On the other hand, Satchel commends Ash in his "fighting Fire with Fire" strategy. Brock, acting as referee, signals the start of the battle. Cyndaquil dodges Magby's Flamethrower, and counters with a Quick Attack; Satchel is impressed. Ash tells Cyndaquil to use a Swift attack, and then its own Flamethrower. Satchel orders Magby to use its Flamethrower once more and the two Pokémon's attacks meet, resulting in an ascending cascade of fire. Magby's move eventually prevails, but Cyndaquil manages to jump out of the way before it is damaged. Ash has his Pokémon use Tackle, and Satchel responds by ordering Magby to use Double Team. Cyndaquil stops in its tracks as Magby's copies surround it, and begin running in a circle. Taking a chance, Ash orders Cyndaquil to go after one of the Magby; Cyndaquil attacks a fake, and Magby's Double Team is disrupted. Appearing from behind Cyndaquil, Magby is told to use its Dynamic Punch. The attack strikes Cyndaquil dead-center; Cyndaquil is unable to battle, and Satchel is declared the victor.
(Source: Bulbapedia)