Ash's Unfezant

Ash's Unfezant is the first Pokémon that Ash obtained in the Unova region.

As a Pidove
Pidove was caught soon after Ash began traveling in Unova in BW002: Enter Iris and Axew. Ash tried to catch another Pidove beforehand, but the rest of the flock attacked himself and Pikachu and flew away, leaving this particular Pidove pecking at the ground. She proved herself to be a strong battler, holding her own against Pikachu before being knocked out by his Thunderbolt and caught by Ash.

Pidove was then sent out in an attempt to rescue Pikachu and Axew from capture by Team Rocket. However, it was easily defeated by Jessie and her newly-caught Woobat.

Pidove has mainly been used by Ash to search for other Pokémon, as seen when she was used to find two wild Darumaka in BW008: Saving Darmanitan From the Bell! and a wild Snivy in BW007: Snivy Plays Hard to Catch!. She played a major role in Snivy's capture, as she was unable to be affected by Snivy's Attract.

Pidove was used against Trip's Frillish in BW010: A Rival Battle for Club Champ!. She was quickly defeated by Frillish's Water Pulse. She was later sent to Professor Juniper's lab in BW018 to make room for Ash's Sewaddle, but was returned to his party in BW021.

As a Tranquill
In A Venipede Stampede!, she helped clear out a swarm of Venipede from Castelia City. She was nearly hit by a Sludge Bomb, but was saved by Trip's Tranquill. She then cleared a few more Venipede and suddenly evolved into a Tranquill.

As of Battling for the Love of Bug-Types!, Tranquill was sent back to Professor Juniper's lab while Swadloon stayed on Ash's team but later in BW039: Archeops In The Modern World! Ash Brought it back to help a revived Archen learn how to fly in the air. It was then seen again in BW057: Scraggy and the Demanding Gothita! where it helped search for Ash's Scraggy, Iris' Axew, and Koharu's Gothita at night.

As an Unfezant
During Ash's Gym battle with Skyla, he used Tranquill to defeat Skyla's Swoobat after it beat Ash's Krokorock it then Battled Skyla's Unfezant and was knocked to near fainting but Ash switched for Pikachu. After Pikachu was defeated by Swanna Ash used Tranquill but she nearly lost, however Tranquill evolved into Unfezant and beat Swanna winning Ash the Jet Badge.

Mystery Egg event
A Japanese event in December 2010 and at Toys R Us in the United States in May 2011 randomly distributed in-game representations of Cilan's Pansage, Ash's Pidove and Iris' Axew. Pidove is always female and has the ability Super Luck.

Trivia

 * Unfezant's ability was revealed in a giveaway of eggs containing the three main character's Pokémon.
 * Unfezant is the first Pokémon Ash caught in the Unova region.
 * Unfezant is Ash's first Unova Pokémon to evolve.
 * Unfezant is one of the few flying type Pokémon caught by Ash at the beginning of his journey, with the others being Starly, Pidgeotto and Noctowl,and Taillow.
 * Unfezant is Ash's first Unova female Pokemon, with the other being Snivy.
 * Unfezant is the first of Ash's Pokémon to be sent to a lab other than Professor Oak's, it was sent to Professor Juniper instead.
 * Unfezant is Ash's first fully evolved Unova Pokemon.
 * Unfezant is the third Pokémon of Ash to evolve during a Gym battle. The others are Ash's Swadloon and Ash's Boldore.