Ash's Pignite

Ash's Tepig is the third Pokémon that Ash obtained in the Unova region.

Biography
Before the events of The Battle Club and Tepig's Choice!, Tepig was tied to a post and abandoned by his Trainer after losing a battle against a Deerling. He ran away after Don George tried to untie him. When Ash visited the Accumula Town Battle Club, he initially mistook Tepig for an Umbreon after seeing it on a security camera stealing food from a warehouse. Ash discovered Tepig eating the bait he and Iris laid out for him and realized that it was actually a Tepig covered in soot. Tepig was extremely thin, as there was rope tied around his snout, preventing him from eating. Ash untied him and carried him back to the Battle Club. When Pikachu was stolen by Team Rocket, Tepig used Ember to rescue him. Ash then proceeded to catch Tepig.

Since Ash promised to use him in his first Gym Battle, Tepig fought against Chili's Pansear in Triple Leaders, Triple Threats!. His attacks did not do much damage to Pansear, whose Fire Punch, Flamethrower and Dig attacks hit Tepig hard. One of these Digs launched Tepig into the air. Ash commanded it to dive down Pansear's hole. Tepig then managed to bite Pansears tail and send it flying. He then defeated Pansear with a combination of Ember and Tackle.

Tepig was confirmed male in Snivy Plays Hard to Catch! when he was hit by a wild Snivy's Attract, forcing Ash to recall him.

In A Rival Battle for Club Champ!, Tepig battled against Trip's Tranquill. Like Oshawott, Tepig was defeated by Tranquill's Super Luck-boosted Aerial Ace.

He battled Lenora's Lillipup in The Battle According to Lenora and was forced back into his Poké Ball by Lillipup's Roar. After Lenora's Watchog defeated Oshawott, Tepig battled Lillipup again, but lost. After training in Rematch at the Nacrene Gym!, he battled Lenora's Herdier. After a short battle, he was sent back by Roar. After Oshawott and Watchog knocked each other out, Tepig battled Herdier again and won using its newly-learned Flame Charge attack.

Tepig was used again in Ash's third Unova gym at Castelia City. He battled Burgh's Dwebble in Battling For The Love of Bug-Types!, and even though it was a -type, he was defeated by its Rock Wrecker.

In Ash and Trip's Third Battle!, Ash used Tepig against Trip's Vanillite. Despite the type advantage Tepig had over Vanillite, the match ended in a draw.

In Battle For The Underground!, while trying to remove Team Rocket from the Battle Subway in Nimbasa City, Tepig learns a new attack, Flamethrower.

He battled alongside Cilan's Pansage in Lost at the Stamp Rally! where they were battling against Subway Masters Emmet and Ingo's Chandelure and Eelektross while in the Battle Subway. It is unknown if they won or lost.

In BW055, he teamed up with Pikachu and Snivy to battle Tobio's Maractus trio. Using their combination of Thunderbolt, Leaf Storm, and Flamethrower, they fought well. When one of the Maractus, Cacchin, panics, they manage to win.

In BW057, he was used to battle against Koharu's Mandibuzz. It used its full attacks against the -type Pokemon and fought well, dodging attacks. When their Brave Bird and Flame Charges collided, he remained victorious.

Trivia

 * Ash describes Tepig as being tenacious, though it lacks confidence when it loses.
 * Ash's Tepig shares the same trait as his other Fire starter Pokémon: being abandoned by their previous trainers; Charmander being abandoned by a selfish trainer, Chimchar being abandoned by it's harsh and abusive trainer Paul and, counted is Cyndaquil since he was about to be captured by an abusive Trainer.
 * Tepig is so far the only Fire-starter owned by Ash, who has yet to evolve.
 * But it is evident in the original ending theme Nanairo Achi that it will evolve into Pignite.