X is a trainer in Kalos.
As a young boy, X won the Juniors' Kalos Pokémon League tournament. Consequently, he was hounded by the press, paparazzi, and fans to the point where he made active efforts to hide from them. One day, he encountered a pair of men associated with the press; the men, curious about Garu and Kogaru, ignored the Kangaskhan's exhausted condition and the protests of X and Pokémon alike as they tried to drag Kogaru out of Garu's pouch. A man then appeared, drove them off, and gave X the Mega Ring.
Another day dawns in Vaniville Town outside of X's window. As usual, he refuses to get up or get dressed, even when Y comes to knock on his window and try to get him moving. Even when X hears sounds of destruction and Y screams that there is danger, he refuses to leave his room.
Y leaves for a moment, and while she is gone, Team Flare attacks X, burning his house to the ground and cornering him against a garden wall. They want to steal the ring on his wrist. Y arrives, and Garu jumps in to defend X and Y from Team Flare's attack. Stricken, X sees Garu's pain, and suddenly Kogaru attacks and defeats Team Flare, forcing them to retreat.
Y forcibly dresses X and puts him on her Rhyhorn to make him leave Vaniville Town.
They travel along Route 1 and arrive at Aquacorde Town, where they stop at an inn for the night. Tierno tries to convince X to choose one of the remaining two of Professor Sycamore's starters, which infuriates X and he refuses. Later, Team Flare admins Mable and Aliana ambush X, attempting to kidnap Kogaru, and X teams up with Professor Sycamore's Chespin to rescue Kogaru and successfully get away from Mable and Aliana.
Once at Santalune City, X puts on the new clothes Y bought for him. He tries to test out Mega Evolution again, battling a wild Litleo and trying and failing to induce the Mega Evolution for Garu and Kogaru.
Viola arrives and offers them a place to stay at her gym. Everyone's willingness upsets Shauna, who thinks that they should stick to their plan not to trust any strange adults; X pats her shoulder, trying to calm her, but Shauna runs off.
The remaining four go to Viola's gym, where X battles and defeats her. X smiles, pleased with his victory, but immediately flinches away and blushes when Viola feigns taking a photo with her fingers and compliments his smile.
Later, X comes across Y, Viola, and Shauna; Shauna has attacked Y with a Honedge, hitting Viola instead when Viola jumps to Y's defense. Shauna, who has been possessed by Celosia's Aegislash through the Honedge in her hand, goes on a rampage. X drags Y off to the side, protecting her. X lunges forward with Garu and Kogaru, about to attack Celosia, when Korrina and her Mega Evolved Lucario appear.
Between Korrina and X, and their Mega Evolved Pokémon, they drive off Celosia. Their alliance ends when Korrina hears that Gurkinn gave X a Mega Ring without the proper ceremony and X is not inclined to have the proper ceremony, and she storms off.
They continue on their way to Lumiose City to see Professor Sycamore. On Route 4, Trevor convinces X to do more experiments with Mega Evolution; they give his Chespin Garu's Mega Stone and see if he Mega Evolves. (He doesn't.) Before they can do more, Chespin spots a Charmander napping in the flowerbeds, and moments later the Charmander rolls over and his tail flame sets the flowers on fire.
Y's Froakie quickly puts it out, and Froakie and Chespin approach the Charmander and begin to chat, clearly familiar with each other. Trevor guesses that the Charmander belongs to Professor Sycamore and insists that they take Charmander with them, putting it in the tent with X on Y's Rhyhorn's back.
X does not emerge from that tent even when they reach Lumiose City and stare at its tall buildings and bustle in awe. He does not emerge even when two masked figures kidnap Charmander and Tierno deftly retrieves it.
When they finally meet Professor Sycamore, X gets out to tell the professor that he doesn't want to keep the Chespin because he doesn't want it to be involved in the fights against Team Flare. Professor Sycamore offers to battle him, but X gets angry when Professor Sycamore will only fight him if he uses Chespin, not Garu. In protest, X sits down and refuses to participate as Chespin fights Charmander. Even so, Chespin's tenacity and refusal to stay down inspire X into trying to help it out by giving commands. Chespin loses, but X is still moved by it and decides to keep it (to Professor Sycamore's surprise) and even asks to keep Charmander (to Professor Sycamore's greater surprise). The professor, although confused, agrees. X nicknames his Chespin "Marisso," and at some point nicknames his Charmander "Salamé."
Once that is settled, X goes to look for his friends, who went to get Trevor's Holo Caster fixed by Professor Sycamore's friend Lysandre. They take the Gogoat Shuttle service to go to the café.
Later, he and his friends go to Prism Tower and wait outside as Professor Sycamore is interviewed for the article about Xerneas and Yveltal's attack on Vaniville Town. After the professor returns, X senses something amiss and rushes inside in time to save Alexa from being killed by a Pangoro sicced on her by her editor. Garu fights Pangoro as Marisso and Salamé fight a pair of Spewpa. X notices how Charmander and Chespin attack only Spewpa, despite his orders to fight Pangoro.
X seems pretty depressed and rather stubborn and stuck in his ways. He is fairly quiet. As the Champion of Kalos' Junior Pokémon tournament, X has prodigious skills in Pokémon battle, but he is humble and never cocky about his title or talent. There are moments when his general apathy gives way to a much more fierce, alert expression than he normally wears, and with expert and efficient skill X will tackle the problem or danger that has caught his attention.
Garu and Kogaru (Kangaskhan)
Garu is X's Kangaskhan and Kogaru is Garu's baby. The two have been with X since he was a young child.
Professor Sycamore gave Marisso and the other starters to Trevor so that X could choose one; this was done in the hopes that it would cheer X up and get him out of his house. However, it backfires, infuriating X, who refuses to accept one. Later, when Team Flare attacks him to abduct Kogaru, X teams up with Marisso to drive Team Flare off. He did not intend to keep Marisso, but after Professor Sycamore makes X and Marisso battle his Charmander, X is impressed with Marisso's guts and grit, and he accepts it onto his team.
X meets Salamé in a flower bed outside of Lumiose City; Marisso and Froakie clearly know it, so he realizes the Charmander must belong to Professor Sycamore. When they return it to him, Professor Sycamore insists on a battle between Salamé and Marisso in the hopes that X will accept Marisso. Salamé defeats Marisso, and X is so impressed with both that he takes both on his team.
X is childhood friends with all four of them; their bond is so strong that even after X locked himself in his house, his friends continued to visit and try to persuade him to come out. Y in particular always comes at least once a day. He and Y became close when they were young and Y's parents, who knew X's parents, took care of X while his parents were away. X has had a serious argument with Tierno about Professor Sycamore's Pokémon. X has also been seen to comfort Shauna when she was upset.
- X is the first male protagonist to take the role of the rival/additional male trainer from the games instead of the player character. This role was once filled by Blue Oak, Silver, Emerald, Pearl and Lack-Two.