Gladion is a pale young boy with yellow hair and green eyes. His hair appears to be cut into squares and is styled for his bangs to perpetually obscure one of his eyes. He wears a grey hooded shirt with a red decoration on it, some black slashed sleeves, slashed black pants and red shoes with grey soles and black laces. He also has a red rectangular bag around his waist. In addition, he also wears a red-brown Z-Ring on his left wrist.
Gladion is a serious and calm trainer, who is looking for himself worthy opponents in Pokémon battles. In the rest, he is a "lone wolf" who avoids meeting with his sister. Despite this, he is noted by others how he still has a kind behavior shown when he told his sister to take care of her Pokémon. While Gladion does not visit his sister often, he swore to protect her, after her encounter with the Ultra Beast.
Gladion, as a young boy, watched as his sister, Lillie, was attacked by an Ultra Beast. Lillie was terrified, while Gladion was not brave enough to defend her. Suddenly, a Silvally arrived, which defeated the Ultra Beast. While Lillie lost memory of the encounter and became scared of Pokémon, Gladion took the Silvally as his own Pokémon, and swore to protect his sister.
Gladion was also motivated to go on a journey to find more about himself, as well as to train alone. Thus, he left Lillie and the mansion.
Sun & Moon
Gladion was walking with Umbreon through the streets when he was ambushed by three Team Skull grunts. Gladion ignored them and continued walking, but the grunts demanded him to hand over his Umbreon. Gladion eyed them, as the grunts sent their Pokémon to attack. Instead, Gladion sent Lycanroc, who used Stone Edge to defeat all three of Team Skull's Pokémon. Gladion continued on and was seen by Team Rocket. He later challenged a sailor, and had his Lycanroc defeat the sailor's Blastoise, impressing the crowd. Ash observed the battle and was told by Rotom that Gladion was the famous trainer of the island. Ash went to Gladion and introduced himself, wanting to challenge him. Gladion ignored him but was called by Lillie, who addressed Gladion as her brother. Gladion was surprised, and when Lillie showed she could touch her Pokémon, Snowy, Gladion simply told how that was great and she should keep it up and refused to visit the mansion. He also saw Ash had a Z-Ring and was told by Ash that he got it from Tapu Koko. Seeing how Ash was important, Gladion decided to at least think of the challenge, then left. During the morning, Gladion sent Umbreon to deliver a letter to Ash to accept the challenge. Ash soon came, as Gladion told he wanted to battle him because of his ties with Tapu Koko. As the two had their Rockruff and Lycanroc battle, Team Rocket came and snatched Lycanroc and Pikachu. Ash's Rockruff managed to Bite the net and free Pikachu and Lycanroc. Gladion decided to finish this, as he used the Z-Ring to have his Lycanroc use Continental Crush, blasting Team Rocket away. Since Ash wanted to use the Rock-type Z-Move, Gladion advised him to challenge the Kahuna of Akala Island. Just as they were about to continue the battle, Lillie came and cheered for her brother. Since Ash had to go to school, Gladion told they should postpone the battle. He shook hands with Ash and left.
As Ash faced Olivia, who had her Lycanroc use Continental Crush, Ash remembered Gladion and his Lycanroc, the former having the latter use the same Z-Move. Gladion's Lycanroc heard Rockruff's howling on Akala Island. Gladion had Lycanroc to go investigate and be back by nighttime. Gladion went to a cave and sent his Type: Null out inside it. However, due to the strain of its helmet, it acted restlessly. Gladion ran over to Type: Null to comfort it and told it that everything would be fine. He exclaimed it would be a problem if someone saw it outside.
Sometime later, Type: Null acted restless again as it sensed the birth of a young Cosmog named Nebby. Gladion reminded Type: Null it would be a problem if someone saw it outside the cave. Gladion managed to calm it down, but it sensed the coming of the Ultra Beast.
Later, Gladion, Type: Null, Lycanroc, and Umbreon were about to battle against a group of Pinsir, but Nebby Teleports Ash, Pikachu, and Ash's Lycanroc to his location. They fall on top of the Pinsir and they attack them out of anger. Gladion's Type: Null was able to chase them away. Then Type: Null started to walk too close to Nebby, frightening it to the point of tears. Gladion calmed Type: Null down, then asked Ash if Nebby is an Ultra Beast. Ash says it might be, but it's not a dangerous one. Gladion starts to get flustered, until Ash tells him that Solgaleo and Lunala trusted Ash to take care of Nebby. Then Ash tells Gladion that Nebby Teleported him, Pikachu, and Lycanroc to his location because Ash wanted to show Gladion his Lycanroc, who is neither Midday or Midnight form. Ash calls it the Dusk Form.
Then Gladion shows Ash an amazing view of Melemele Island, and tells him that they're at Ten Carat Hill. Ash tells Gladion that Lillie's doing fine, and that she managed to touch Pikachu, as well as taking care of Snowy, and was the one who named Nebby. Gladion doesn't understand why she named an Ultra Beast, then tells Ash that Lillie was attacked by an Ultra Beast a few years ago, and was saved by Type: Null. The incident caused her to become unable to touch Pokémon, and Gladion vowed that he would protect her. Gladion promises that if Nebby shows any Ultra Beast trait, he and Type: Null will eliminate it before it can cause harm. Gladion begins to wonder what kind of trainer is Ash since Tapu Koko personally gave him a Z-Ring, owns a Lycanroc of an unknown form, and Solgaleo and Lunala entrusted him with Nebby. Ash doesn't anwser his questions, but changes the subject by challenging him to a battle since Team Rocket interrupted the last one, which Gladion accepts.
Gladion uses his Type: Null for the first time in an official battle while Ash uses his Lycanroc. Gladion's Type: Null proves to be a powerful opponent, landing some powerful attacks, and dodging most of Lycanroc's despite its heavy mask. Type: Null's Crush Claw eventually knocks Lycanroc into a nearby puddle, messing up its fur. With its fur ruined, Lycanroc flies into a fit of rage and attacks Type: Null without Ash's commands, forcing Ash to restrain Lycanroc. Lycanroc's rage frightens Nebby, causing it to release a powerful screech which cleans Lycanroc's fur, calming it down. Ash and Gladion decide to continue the battle, and Type: Null eventually defeats Lycanroc. After the battle, Ash decides to head back to Professor Kukui's house. Gladion tells Ash not to say a word about this to anyone, especially Lillie.
A few days later, Nebby teleports Lillie to Gladion's location after she strongly desires to see him again. Gladion asks Lillie why she's there. Lillie is about to express her desire to spent time with him like before, but Type: Null leaps right right in front of her. The sight of Type: Null causes Lillie to partly remember the incident that caused her fear a few years ago. Gladion rushes over to a terrified Lillie, but Nebby Teleports Lillie back to her friends before he could reach her. After returning to her friends, Lillie realizes that the forgotten memory causes her to become unable to touch Pokémon again, even Snowy.
Later that night Gladion is furious with Ash for letting Nebby take Lillie to him. Gladion thinks that it would've been better for Lillie if she never remembered the incident. After lashing out on Ash, Gladion returns to his hotel room where Faba is waiting for him. Faba orders Gladion to return his Type: Null. Gladion refuses and uses Lycanroc and Umbreon to protect it. Faba uses his Alakazam and Hypno to battle Gladion's Pokemon. Faba's Alakazam and Hypno's quickly overpower Gladion's Lycanroc and Umbreon with Hypnosis and Psychic. Gladion attempt's to use his Type: Null as a last resort, but Faba's Hypno uses Hypnosis to render him unconscious. Gladion struggles to resist the powerful Hypnosis, but his vision becomes blurry and eventually fall's down unconscious, allowing Faba to steal his Type: Null.
The next day, Gladion goes to Aether Paradise where he see's his mother Lusamine in her office. Gladion angrily demands to know where Type: Null is, but Luasmine is completely unaware of the situation. Though she remembers that it was a Pokémon that Faba created to fight Ultra Beast, but Faba told her that it failed. Gladion correctly assumes that Faba was lying, because Type: Null saved Lillie from an Ultra Beast a few years ago. Then while the two are searching for Type: Null in Faba's office, Gladion informs Lusamine of the incident that happened a few years ago. Gladion furiously points out the Lusamine should've known this despite Faba's lies, and chastisis her for her obsession with Ultra Beast cause Lillie to become suddenly unable to touch Pokémon. Lusamine apologizes to him, but Gladion states that he's not the one that she should apologize to. Gladion finds his Type: Bull's Premiere Ball, but his happy reunion is quickly interrupted by an alarm coming from the basement. Gladion and Lusamine rush down there where they find Lillie being held in the air by Faba's Alakazam's Psychic, and Ash, Pikachu, Snowy, and Nebby being held down by Faba's Hypno's Psychic. Gladion sends out Type: Null to save Lillie, who finally breaks free from it's mask to save Lillie from Alakazam's Psychic. The now evolved Silvally successfully saves Lillie, causing her to fully remember the incident that happened a few years ago. Gladion equips Silvally with a Dark-Memory Disc, changing it into a Dark-Type, and defeats Faba's Alakazam and Hypno with a newly learned and super-effective Multi-Attack, freeing Ash, Pikachu, Snowy, and Nebby from Hypno's Psychic. Having learned that the whole ordeal was a misunderstanding, Lillie apologized to Silvally and thanked it for saving her twice, and gave Silvally a hug, much to everyone's surprise. Not only is Lillie able to touch Silvally, she is once again able to touch Snowy, Pikachu, and even able to touch Nebby without fear. Gladion and everyone else is happy for Lillie for finally overcoming her fear of touching Pokémon once and for all.
Sometime after Faba escaped, Gladion has been searching for him nonstop. He eventually visits his mother in her office, who ask's if they found Faba. Lusamine say's no, but their still searching everywhere. Gladion is about to continue his search, but Lusamine stops him from leaving. Telling Gladion that The Aether Foundation is looking for Faba, but Gladion wants to catch Faba before he could cause anymore trouble and leaves.
A few hours later, Gladion heads to the Pokemon School. Lillie tells her big brother that Faba kidnapped Nebby then disappeared somewhere. Gladion believes that they might be at Aether Foundation. A jet from Lillie's Mansion arrives at the Pokémon School to take them to Aether Paradise as quickly as possible. Gladion tell's Lillie to stay behind, but Lillie want's to save Nebby too and assist that she comes along. Gladion is surprised by his little sisters determination, and let's her come along. Along the way, they inform Lusamine of the situation.
Along the to the basement, Gladion correctly assumes that Faba plan's to use Nebby to summon another Ultra Beast. When they arrive in the basement, they see Faba using a machine that's trapping Nebby and using it's power to create an Ultra Wormhole. While Ash tackle's Faba, Gladion's Umbreon destroys the machines that's trapping Nebby with Shadow Ball. After Nebby is freed, it evolves into Cosmoem, much to everyone's surprise. However, the machine absorbed enough energy to create an Ultra Wormhole and a Nihilego appears, the same Ultra Beast that attacked Lillie a few years ago. Nihilego then attacks everyone, then Gladion sends out Silvally to protect Lillie. Nihilego proves to be too strong despite everyone's attempt to get it out of their world, and descends down to try to attack Lillie. Gladion is determined to protect his little sister, by letting Nihilego take him away, but Lusamine pushes her son out of the way and gets carried away to the Ultra Deep Sea, leaving Lillie and Gladion horrified.
After Lusamine's abduction, Gladion and Lillie are taken home to rest up. Ash offers to help them save Lusamine, but Gladion rejects his offer cause it's a family crisis. At night, Gladion walks into Lillie's room, who lies to him about going to bed. But Gladion knows it's a lie by looking at her clothes and new hairstyle. Though Lillie still lies to him by saying it's her sleepwear, Gladion asks her how will she open a Ultra Wormhole. Lillie admits that she doesn't know, but Gladion says he does know. Gladion decides to go on his own, but Lillie insists on going with him. Gladion let's Lillie come along with him and the two run away from the mansion, riding on Silvally.
The next day, they arrive in Vast Poni Canyon on Poni Island, attempting to open an Ultra Wormhole at The Altar of the Sunne. First they find an old door with statues of Rowlet, Litten, and Popplio in front of it. Lillie thinks that it's a puzzle that they must solve by pushing the statues in place, but Gladion simply pushes the door open. Then Gladion tell's Silvally to push the Popplio statue in place. When Silvally does so, it's revealed to be a spike trap. Gladion tell's Lillie to be careful and not touch anything. Then they see an entrance on the other side of a cliff. Lillie thinks there is an invisible bridge connected to the other side, and drops some sand in order to find it. But Gladion tell's her to get on Silvally, and it leaps the two to the other side of the entrance. Gladion tell's Lillie that there was a bridge, but it was destroyed a long time ago. Lillie begins to think that's she's only slowing her brother down, and wonders if she should stay behind. Gladion knows that Lillie won't stay put even if he told her it, and the two proceed forward. Then they come into an old ruin where they are ambushed by a group of Jangmo-o, Hakamo-o, and their leader Totem Kommo-o. Lillie sends out Snowy to battle the Jangmo-o, and Hakamo-o while Gladion and Silvally deal with Totem Kommo-o. Totem Kommo-o's hard scales are too hard for Silvally's Crush Claw, and Totem Kommo-o doesn't take much damage. Lillie tell's Gladion that if Silvally can change into a Fairy-Type, they might be able to beat Totem Kommo-o. Gladion is about to equip Silvally with a Fairy-Type Memory Disc, but a Jangmo-o disarms him and the Memory Disc land underneath Totem Kommo-o. Lillie and Snowy create a path by attacking the Jangmo-o and Hakamo-o with Powder Snow, then they freeze the ground with another Powder Snow. Gladion and Silvally skate across the frozen floor while Totem Kommo-o charges up a Clanging Scales attack. Gladion retrieves the Memory Disc and equips Silvally with it a split second before the Clanging Scales attack can hurt them. Silvally defeats Totem Kommo-o with a super effective Multi-Attack before Totem Kommo-o uses another Clanging Scales attack. Lillie congratulates her big brother for beating the Totem Kommo-o, but Gladion gives the credit to Lillie. However, the ceiling begin to crumble down on them. Lillie and Gladion ride on Silvally to reach the exit, but are about to get crushed by a falling boulder. Thankfully they are saved by an Electro Ball. After they barely make it out, Ash and his Classmates, along with Professor Kukui followed them to Poni Island, because they want to help the siblings save their mother. Gladion reminds Ash that this is a family situation, but Ash states that people in Alola share everything including family situations, and they stay and help each other out. Although Gladion still refuses to let them help, Lillie feels like that they'll need their help to save their mother, and they want to save her as mush as he does. Moved by her speech, Gladion reluctantly let's Ash and the others help. When they all arrive at the Summit of The Altar of the Sunne, the Guardian Deities of Alola show up for an important meeting.
The group informs the Guardian Deities of the current situation, and asks if they can use Solgaleo's power to open an Ultra Wormhole. The Guardian Deities create field surrounding The group and show a screen that shows the events of Ash's dream of Solgaleo and Lunala creating Nebby, and reveals that the Guardian Deities were there when Ash first encountered Nebby. Suddenly, Nebby starts to glow and comes out of Ash's bag. Then Tapu Lele and Tapu Fini begin to bless Nebby, but this causes Gladion to get impatient and tell's them go faster, earning him an up close glare from Tapu Koko. Lillie tell's her brother to wait a little longer and the Guardian Deities know what their doing, calming him down.
After Professor Kukui splits from the group to help Professor Burnet, the Guardian Deities meditate until The Altar of the Sunne shoots a beam at Nebby that evolves it into Solgaleo, much to everyone's amazement. Then after Ash gives it some Sugar Star's, Ash, Lillie, and Gladion ask Nebby to take them to Ultra Deep Sea to rescue Lusamine. A Solgalium Z descends down and Ash tries to place it on his Z-Ring, but it won't fit. So The Guardian Deities upgrade it to a Z-Power Ring, startling everyone. After Ash places the Solgalium Z into his new Z-Power Ring, Gladion excitedly asks Nebby if this means if they'll be able to go where his mother is at now. Nebby wants all of them to get on it's back, and Gladion tell's everyone to get their Pokemon into their Pokeball's. After everyone except Ash recalled their Pokemon, they all mount up on Nebby's back all ready to go. Ash and Nebby perform Searing Sunraze Smash to open an Ultra Wormhole, and the kid's ride on Nebby through Ultra Space, leaving Professor Kukui and Professor Burnet behind.
After they arrive in Ultra Deep Sea, they are surrounded by a horde of Nihilego. Thankfully the Ultra Beast don't attack the humans, and they start discussing their plan to find Lusamine. After agreeing to stick together, everyone sends all of their Pokémon out of their Pokeballs. Lusamine suddenly appears in front of them, but she has fused with the Nihilego that captured her, and her personality has reverted to a child like state. Lillie run's to her mother, forcing Ash and Gladion to go after her. But Nihilego blocks the way with boulders, Ash protects Lillie while Gladion's Umbreon destroy's the boulders with Dark Pulse. Gladion thinks that Nihilego is the cause of Lusamine's strange behavior, and fears it might be draining her energy. Lusamine runs away, leaving behind a trail of boulders wherever she goes. The children use that trail to follow her, and while chasing Lusamine, they wonder if she's being controlled by Nihilego. Gladion thinks that part of her real personality is still being shown because of her life long dream to meet an Ultra Beast. Because her dream finally came true, Gladion believes Lusamine isn't aware she's being controlled. Gladion also assumes that the reason that Lusamine is attacking them is because she thinks their trying to take the Ultra Beast away from her. Lusamine then summons more rocks to protect herself. All attacks are proven to be useless this time, until Nebby uses Sunsteel Strike to destroy the rocks. Lusamine sends out her Salazzle, who is under Nihilego's control to battle them. Kiawe, Marowak, and Turtonator stay behind to battle her, while the others ride on Nebby to chase Lusamine. Lusamine sends out her Milotic, Mismagius, and Lilligant to battle, forcing Lana, Popplio, Sophochles, Togedemaru, Charjabug, Mallow, Steenee, Litten, and Rowlet to stay behind and fight them. Ash, Lillie, and Gladion continue to chase Lusamine while riding on Nebby. Lusamine sends out her Absol, who is Umbreon's sparring partner. Gladion, his Lycanroc, Umbreon, and Silvally stay behind to battle Absol while Ash and Lillie continue to chase Lusamine while riding Nebby. Absol uses Ice Shard on Silvally's feet, then use's mean look on Lycanroc and Umbreon, immobilizing them.
With all three of his Pokémon immobilized, Absol continues to attack them. Gladion equips Silvally with a Fire Memory Disc to change it into a Fire-Type. Silvally breaks free from the ice, and attacks Absol with Multi-Attack, freeing Umbreon and Lycanroc from Mean Look. They continue to attack Absol until Gladion and Lycanroc use Continental Crush to defeat it. However, after all of Lusamine's Pokemon with the exeption of Clefable are defeated, they immediately come back with full health. Gladion realizes unless if Nihilego is defeated, the fight will never end. Gladion leaves with Silvally, while Lycanroc and Umbreon deal with Absol.
Then Gladion meets up with Lillie, Snowy, Ash's Lycanroc, and Lusamine's Clefable, whom Lillie managed to free from Nihilego's control. Then they meet up with Ash, Pikachu, and Nebby. Gladion informs Ash of the situation going on below the, and is worried about the others. Ash sends Nebby to get Lycanroc and help them out. After Nebby and Lycanroc leave, Lillie begin begins to walk towards Ash. Ash warns her about the pool of poison in front of them, but Lillie and Snowy hold on to Clefable and skips across without getting poisoned due to its ability Magic Guard. Gladion equips Silvally with a Steel-type Memory Disc so they could also run across without getting poisoned. Gladion exclaims that he trained Silvally to battle Ultra Beast, and the time has finally come. However, Lusamine rises up, creating a mountain of rocks. Lillie climbs up because she has something to say to her mother. Gladion and Ash will attack if Lillie is in danger. Lusamine continues to make obstacles until Lillie shout out that she hates her. Lillie tell's Lusamine that she's acting more like a spoiled baby than she ever has, and now she's a marionette that has no will of her own. But Lillie knows that Lusamine is a strong person, and should be able to resist Nihilego's control on her own. Lillie's words snap Lusamine out of her state, and reaches out her hand. Gladion is happy to see his mother has snapped out of her state. However, Nihilego refuses to let Lusamine go and completely engulfs her. Nihilego attempts to attack Lillie, thankfully Gladion and Silvally save her in time. Nihilego grows bigger and covers itself with more rocks and spikes. Gladion knows that Nihilego won't let Lusamine go because it wants to learn about humans, like how Lusamine wanted to to learn about Ultra Beast. Nihilego shoots a ton of spikes to hurt them, then it's wall's grow bigger and forming more rock formations. Ash suggests that he and Gladion use a Z-Move at the same time, but Gladion has already used Continental Crush on Absol earlier. So while Gladion and Lillie distract Nihilego, Ash and Pikachu will use Gigavolt Havoc on it. Nihilego shoots more spikes at them, but Silvally counters it with Air Slash. Ash is about to use Gigavolt Havoc, but his Electrium-Z changes into a Pikashunium-Z, so they use 10,000,000 Volt Thunderbolt for the first time instead, much to their surprise, but it reverts back into an Electrium-Z afterwards. The powerful Z-Move finally defeats Nihilego, allowing Lillie and Gladion to pull their mother out of it. Gladion and Lillie find their mother unconscious and covered in black ink, and Nihilego flies away in defeat. As soon as Lusamine wakes up, all of her Pokémon are freed from Nihilego's control. Gladion and Lillie help their mother stand up, and Lusamine apologizes to them. Gladion watches as his sister cries in her mothers arms, then everyone else including Lusamine's Pokémon meet up with them.
Then everyone returns back to their world riding on Nebby's back where Professor Kukui and Professor Burnet are waiting for them. The Professors are glad to see that Lusamine is okay. Lusamine gives the credit to the kids for rescuing her. After the Ultra Wormhole disappears, Gladion is displeased to see that Sophochles has brought a rock from Ultra Deep Sea back with him. Then a helicopter arrives to take Lusamine back to Aether Paradise for treatment with Lillie and Gladion tagging along. After their mother gets better, Lillie and Gladion go their separate ways. Lillie goes back to Pokémon School with her friends, and Gladion decides to participate in the Island Challenge.
Later, when Ash and Pikachu are taking a late night stroll on the beach, they are greeted by Gladion and his Umbreon. Ash tells Gladion that Professor Kukui and Professor Burnet are getting married in the morning, and invites him to come see it. But Gladion tells Ash that he's going on a journey, because he can't relax after seeing the 10,00,000 Volt Thunderbolt Z-Move Ash and Pikachu did earlier. Gladion is going to do The Island Challenge, and tells Ash to congratulate Professor Kukui and Professor Burnet for him. As Gladion leaves, Ash promises Gladion that he'll continue his Island Challenge too, and offers to challenge him to another battle someday, causing Gladion to smile and then waves goodbye.
Alola Island Challenge
Gladion is the only rival to be related to one of Ash's traveling companions.