Nate's Riolu

Nate's Riolu is Nate's first and main Pokemon that has been with him since childhood.

History
Riolu first appeared in A New Generation, where it watched its trainer defeat a Herdier with his Braviary. Later on when Nate is challenged by Hugh, he uses Snivy while Nate chooses Riolu. Despite its incredible battle skills and speedy reflexes, it was defeated by a powerful Leaf Tornado, giving the win to Hugh.

In Enter the New Gym Leader - Cheren!, Riolu was in a training battle with Braviary for Nate's upcoming Gym battle with Cheren. Despite having a type disadvantage against Flying-type attacks and the fact that Riolu had gotten weak by Aerial Ace, Riolu uses Copycat to retaliate with the same move that it copied. Cheren described this as Riolu's best advantage when it comes to battle.

Later in the next chapter, Riolu is the second Pokemon used during Nate's Gym battle against Cheren's Minccino in Aspertia City. Riolu takes damage from Minccino's attacks: Tail Slap, Bullet Seed, and Focus Blast. It then utilizes its other attacks, but are unable to defeat Minccino due to its faster agility. After taking damage from Hyper Voice, Riolu uses Copycat and uses the same attack and then after- wards uses Force Palm to successfully paralyze her. When they colide with Giga Impact and Vacuum Wave, the two opponents fainted simultanously.

Trivia

 * Rio is the only Pokemon who he had obtained previously up to its debut.