AJ's Serperior

 AJ's Serperior (Japanese: アジェイジャローダ Ajiei's Jalorda) is the Pokémon that AJ ever owned.

Unova
, as a, was to rookie Trainer AJ at 's laboratory in. Moments later, AJ and Snivy battled against Ryder and his Incineroar. AJ starts the battle by ordering his Snivy to use which strikes Incineroar square on its chest, but Incineroar seems unfazed by the attack. AJ continues the assault with, but Incineroar easily bats the attack away with its hands. AJ changes his tactics and commands Snivy to use to increase its attack power, and orders three more Growths, before commanding a, but Incineroar grabs the vines and pulls Snivy towards him, who gets sent flying towards Incineroar, who uses , defeating Snivy with a single hit. AJ recalls Snivy and thanks him for the effort, and admits that Ryder was truly on a different level, but vows to become stronger and the two shake hands before AJ leaves for the nearest.

Shortly afterwards, Snivy into, and the two battled against Ryder once again at the  in , where Sevine faced off against Ryder's Snivy. Snivy uses, but Servine dodges them completely. She then attempts to use, but misses and Servine follows up with a Leaf Tornado. The tornado, once again, draws her into the vortex then slams her onto the ground. Ryder asks Snivy to use Vine Whip, and Servine, once again, dodges it easily like it had before. Next, while Servine is distracted by her Vine Whip, Ryder tells Snivy to use. Snivy fires the attack, and luckily, as Servine is male, he becomes infatuated with Snivy, and he is thus unable to attack. Eventually with a series of Vine Whips and a well-aimed Leaf Blade, Servine succumbs to Snivy's attacks and fainted, leaving AJ with three Pokémon.

Servine and Snivy battled in a rematch while Ryder was en route towards. The battle begins with Servine using where Ryder counters it by having his Snivy use. The two attacks collide and AJ immediately orders his Servine to use. Ryder orders his Snivy to dodge and then use. AJ counters the hearts of the Attract attack by once again using Leaf Tornado, causing all of the hearts of the attack to vanish and render the Attract attack useless. AJ explains that he won't fall for the same strategy again and that he learned from his mistake last time. He then orders his Servine to once again use Cut. Ryder orders his Snivy to. Snivy's Leaf Blade overpowers Servine's Cut and Servine gets sent flying, before Snivy finishes it off with Leaf Storm, which gives Ryder the first win.

When AJ registered to participate in the, Servine was revealed to have evolved into Serperior, and was used throughout the entire tournament. During AJ's first round match-up, Serperior battled against 's. Serperior uses to lower Darmanitan's defense and uses a match-winning. When the smoke clears, Darmanitan is no longer able to battle and AJ is victorious.

In the next round, AJ's Serperior faces off against Manning's and wins despite the type advantage with  followed by. In the semi-finals, AJ and Serperior battle against Angus and his. Serperior uses and Solar Beam, and despite sustaining damage, Simisage endures the attack. Angus has Simisage use and, but Serperior dodges both attacks, and Serperior easily defeats Simisage with. comments that AJ battled well, but power isn't everything. AJ glares back at the, thinking to prove him wrong.

In the finals, AJ and Serperior battled against Ryder and Emolga. To start, Ryder commands Emolga to use, which Serperior dodges. Ryder then commands Emolga to use, which Serperior again dodges. Everyone appears remarked by Serperior's lightning speed.

AJ commands Serperior to use Solar Beam, but Emolga steals Serperior's thunder and dodges. AJ then has Serperior use, which just barely hits Emolga. However, Emolga fires back with another Discharge, but Serperior dodges, making Emolga follow up with Hidden Power and, but both get dodged by Serperior. Serperior uses Leer, and Emolga dodges, only to make Serperior use another Dragon Tail, which Emolga also dodges. Emolga uses another Discharge but Serperior dodges again. Despite her exhaustion from her many dodged attacks, Emolga uses yet another Hidden Power, which as expected, is dodged by Serperior. Serperior uses Leer and Ryder again commands Emolga to dodge by flying up in the air. With Emolga in a vulnerable position, AJ knows this is his chance to strike, so he commands Serperior to use Solar Beam, which lands and hurls Emolga onto the ground.

Emolga gets up, and Ryder tells him that she needs to stay strong if she wants to beat Serperior. With Emolga back in battling position, Ryder decides to unleash Emolga's new attack: and Emolga gets commanded to unleash multiple Air Slashes at once. However, Serperior moves so fast that he fades into thin air and dodges the surrounding Air Slash attacks, and is subsequently commanded by his Trainer to use Frenzy Plant. The move lands and knocks Emolga out, making AJ the winner and Ryder the runner-up of the Junior Cup.

Ryder recalls Emolga and falls beside himself since he lost to AJ yet again. After this, Alder gives AJ the Pokémon World Tournament Junior Cup Trophy for winning, and explains that their battle will begin immediately. Finally experiencing the moment he has been waiting for since the start of the tournament, he rants about how he will easily beat Alder and become the champion. As Alder and AJ enter the battlefield, Alder sends out, and AJ chooses Serperior again. With everyone watching, AJ commands Serperior to use Solar Beam. Alder tells Bouffalant to rush toward Serperior, but Solar Beam is dispelled upon striking Bouffalant. AJ states that Bouffalant's Ability is, and Ryder wonders why he used aGrass-move when he knew it would not work on Bouffalant. Alder confirms the Ability and states that Grass-type attacks increase attack power instead of doing damage. Alder goes on to say that Bouffalant is unstoppable at this point, but AJ claims he will prove him wrong and that he is more powerful than Alder. Alder tells him to take his best shot to prove it.

Frustrated, AJ orders Dragon Tail, which hits Bouffalant's afro, but it is once again unfazed. Alder tells AJ to show him what else he has got. Serperior uses Leer to lower Bouffalant's defense, then jumps into the air and attacks with Dragon Tail. In his mind, AJ states that his strategy was to purposely activate Sap Sipper so that Alder and Bouffalant would let their guard down. Though Serperior is airborne, Dragon Tail strategically hits Bouffalant's unprotected underside, knocking it away. However, Bouffalant lands on its feet, surprisingly unscathed by the attacks. Alder commends the power, speed, and strategy AJ used, but notes that though they would take out a normal Pokémon, AJ is fighting a champion. Alder orders and Bouffalant charges forward. AJ desperately tells Serperior to dodge, but Serperior is struck and knocked out, giving Alder the win.

Alder congratulates his Bouffalant as it happily licks his face. AJ approaches Alder to ask what he did wrong for Alder to beat him so easily, and the champion replies that he had not done anything. Alder asks a confused AJ if he has any respect for him at all, and that he needs to think about what he has learned. Alder then asks him if he cares for Serperior. AJ is surprised, but before he can respond, Alder tells him that Serperior obviously cares very much for him and that he needs to feel that bond. AJ replies that he does, and Alder responds that that is probably where his strength lies.

Serperior was chosen as AJ's final remaining Pokémon during his battle against Ryder at the finals of the, facing off against Ryder's Incineroar. Incineroar starts out with, but Serperior dodges. Incineroar then uses, but gracefully slides around Flare Blitz to dodge. Serperior then uses back-to-back to decrease Incineroar's defense, and subsequently follows up with, which connects with Incineroar and causes serious damage. As Incineroar slowly gets back to his feet, AJ quickly commands and Serperior squeezes Incineroar, who cries out in pain. As Serperior continues to squeeze him, Ryder commands Flamethrower, but Incineroar is unable to as Serperior is squeezing him too tight for him to unleash any attacks. AJ then commands Serperior to toss Incineroar aside and finish him off with, and Incineroar gets knocked out by the powerful attack, therefore Serperior finally gains his first victory over Incineroar.

Ryder recalls Incineroar and thanks him for the effort, and immediately chooses Pignite as his fifth Pokémon. Serperior starts off with another Leer, which hits and decreases Pignite's defense. AJ then commands Dragon Tail, but Pignite manages to catch Serperior's tail just in time and unleashes a point-blank Flamethrower, sending Serperior flying back. However, Serperior quickly recovers and uses another Leer, and Pignite's defense continues to decrease. Pignite then fires off numerous and  attacks, but Serperior successfully manages to dodge them all, and subsequently defeats Pignite with a single Frenzy Plant attack.

With Ryder down to his last Pokémon, Ryder chooses Dragonite and Dragonite lets out a roar upon being called. AJ remarks he knew that Dragonite would be his final choice; the moment that Incineroar was brought earlier, was the moment AJ realized that Dragonite would be his final choice, as Dragonite was pratically the strongest Pokémon in his team besides Incineroar. Starting the battle, Dragonite strikes first with. Wanting to wrap the battle up as fast as possible, Ryder has Dragonite use two additional Thunder Punches. Serperior looks like it is almost beaten, so Ryder orders Dragonite to go in close with another Thunder Punch, but Serperior manages to slide away. Jumping up, Serperior comes in from above with Dragon Tail, throwing Dragonite across the stage. AJ has Serperior follow up with Frenzy Plant. At the same time, Dragonite lets off an. The attacks collide in midair and explode, throwing both trainer's Pokémon away. Both Pokémon are able to get up, but Serperior looks like he is struggling more.

Both Pokémon run toward each other. Serperior attempts to land a Dragon Tail, but Dragonite jumps over Serperior and dodges the attack. Not wanting to give up, Serperior follows and grabs Dragonite, tossing Dragonite high into the air with its tail. Dragonite somersaults in the air and lands lightly on his feet. Following up, Dragonite hits Serperior with a powerful Flamethrower and goes in close to hit with a Thunder Punch. Serperior gets sent flying back, as Ryder orders Dragonite to end it all with. As Dragonite flies up and rains down with the attack, AJ commands Serperior to use Frenzy Plant to counter. Just as Serperior prepares to unleash the attack, it suddenly stops and AJ gasps in shock as he notices that Serperior has become by Dragonite's Thunder Punch. As Serperior opens its eyes after suffering from paralysis, it looks up just to see Dragonite inches away from its face, as Dragon Rush connects with full force, causing a series of explosions, that even Ryder and AJ are caught in the middle. The audience gasps as they all stand up from their seats as the announcer roars in concern, as both Ryder and AJ are within the smokescreen caused by the explosions.

After an apparent neverending amount of time, the smoke finally settles, and both Trainers are alright, as they are staring down at the field without blinking an eye, and when the smoke clears off completely, the crowd sees that Serperior is lying down, knocked out, while Dragonite stands triumphantly over the Regal Pokémon, as the referee declares Serperior unable to battle, and declares Dragonite as the winner, and Ryder as the victor of not only the match, but of the.

Personality and Characteristics
Serperior is quite confident and self-righteous, as seen when AJ chose him over the other starter Pokémon. He has retained this trait after evolving. Serperior's most notable trait as it further evolved is his overwhelming speed, having swept through the entire without being touched once. Also, Serperior has very little trouble dealing with opponents who have a type-advantage, a further testament to his strength, seen as when Serperior defeated Ryder's Incineroar and Pignite in quick fashion.

True to his species norm, Serperior holds his head high pretentiously while fighting and tends to stay elegant at all times. He does not take most opponents seriously, unless said opponent is particularly powerful, as seen when he was up against 's, showing signs of shock when his didn't phaze his opponent. More signs of his species norm were seen after Serperior was defeated when it was bowing his head to Alder when the talked to him and stroked his chin.