Ash's Quilava

While training for the Sinnoh League, Ash brought his Cyndaquil with many of his other Pokémon. However, Team Rocket tried to cause problems and Cyndaquil evolved in order to stop them. Quilava has numerous powerful attacks such as Flame Wheel at its disposal, showing that it has completely overcome its previous hindrances in its base form and is sure to be a powerful Pokémon within Ash's team. Ash Caught it in Good 'Quil Hunting as a Cyndaquil. It's most likey that he caught it on Route 33. It currently is at Professor Oak's Lab. It also learned Eruption and Aerial Ace. Like Dawn's Quilava, Ash's Quilava learned Eurption after evolving from Cyndaquil.

As a Cyndaquil
When it was a Cyndaquil, it was one of Ash's most powerful Main Pokémon for Johto.

Moves
Quilava's most powerful moves are Flamethrower and Eruption, but it had trouble getting the fire on its back started early on after it was captured.
 * Flamethrower
 * Tackle
 * Agility
 * SmokeScreen
 * Swift
 * Quick Attack
 * Flame Wheel
 * Eruption
 * Aerial Ace

Trivia

 * Quilava is Ash's only non-flying type Pokemon to learn Aerial Ace.