Hau is described as a big-hearted boy who quickly befriends the player once they move to the Alolaregion. He is the grandson of Hala, who is the kahuna of Melemele Island; and his favorite food is malasada, a famous treat in Alola. One of the villagers in Iki Town, where they live, comments that as a boy, Hau had once witnessed Hala in a rage, which frightened him to the point of tears. Nothing Hala did could comfort him, which he claims is the reason why Hala is "too soft" on Hau.
Once the player has chosen a starter Pokémon, Hau will challenge the player using the starter Pokémon weak to the player's choice. Upon losing, he quickly shrugs off his defeat as he says that he is having fun. He also embarks on the island challenge at the same time as the player, and completes the challenges at around the same pace, until at the most Sophocles's trial. Hau's happy-go-lucky attitude affects most of his early battles as he didn't mind losing and just wants to enjoy his adventure, something that irritates Gladion after their first battle.
Hau joins the player on a tour of Aether Paradise after finishing their Akala Island trials. He is shocked to hear from Lusamine that she is over forty years old, and also comments that she looks like Lillie without knowing of their connection.
When the Aether House is raided by Team Skull, Hau manages to win a battle against a Team Skull Grunt, but says that battles he can't afford to lose aren't any fun. Before the player returns from Po Town, Hau loses a critical battle against Team Skull Admin Plumeria when she and her grunts kidnaps Lillie, and is left depressed and in doubt of his own skills because of this. He feels weak for being unable to save Lillie.
Hau joins the player and Gladion in their attempt to rescue Lillie and her Cosmog from the Aether Foundation. Although he starts to doubt about himself and at first hesitates to accompany them because he would probably feel like a burden. During the infiltration in the Aether Foundation, he is constantly irritated by Gladion's orders and lack of explaining, both constantly end up arguing. Hau manages to take down several Aether Foundation Employee with Gladion and the player before reaching Lillie. He is surprised when Lusamine reveals that Lillie and Gladion were her children. When Lusamine attempts to open up Ultra Wormholes across Alola, Gladion orders Hau to keep Guzma busy while he deals with the recently arrived Nihilego, but Lusamine and Guzma manage to achieve their objective and escape.
When the player is about to travel to Poni Island, Hau expresses his intention to hold back the island challenge and train himself with Hala instead. After everything that happened Hau has realized how weak he is, especially when compared to the player or Gladion. So he must get his act together if he wants to achieve his goals. Hau stops his journey and sets out to train.
When the player is about to enter the Pokémon League building, Hau catches up to them and challenges the player to another battle to decide who will face the league first. This time, Hau takes the fight more seriously and asks the player to use all their strength. Upon losing, Hau reveals that this time he really wanted to beat the player and reaffirms his determination to get even stronger. He finally takes battles more seriously. Hau says goodbye to the player and spurs them on for his Pokémon League challenge. The day after the player becomes the Champion, Lillie departs for Kanto without having been able to say it to the player and Hau, who is devastated by this and is left in tears after Lillie's ship has left.
At the start of the post-game, Hau appears at the player's house to give them the Z-Crystals to the starter Pokémon they didn't choose at the start of the game, saying that he got them as rewards after having finally had a serious battle with his grandfather. After asking the player and their mom about Kanto, he decides to train hard to one day travel there to find both Lillie and his father, who is a strong Trainer who had hated being the son of a kahuna and thus had moved out of Alola. Hau also warns that he will try to beat the player and snatch them their Champion title, now that he is strong enough. Afterwards, Hau can be found at Iki Town, training a pair of reformed Team Skull Grunts in Alolan sumo.
Hau is one of the possible NPCs who can challenge the player for the title of Champion, implying that he has completed all his island trials. He will always be the first challenger to appear after the player has defeated the Elite Four for the second time. There, Hau has achieved everything he wanted, but he warns that he still has an opponent to defeat, the player.
After the player has obtained their starter Pokémon from Professor Kukui on Route 1, Hau will appear and choose his own starter from the remaining two (which is always the one weak to the player's choice) before challenging the player into their first Trainer battle. When his grandfather shows up late in Iki Town, Hau berates him for his lateness. After the player has defeated Hala, instead of boarding Kukui's boat, Hau will invite the player to ride Mantine to Akala Island.
On Ula'ula Island, Hau will give the player a Lycanium Z after battling them after their arrival on the island. After the player defeats Guzma at Malie Garden, Guzma notices Hau and tells him that he shouldn't take the island challenge just because he's a kahuna's grandson. After the Aether Paradise incident, Hau realizes that he keeps failing to protect those he cares about, and becomes even more determined to become stronger.
When Necrozma fuses with Nebby during the game's climax and Ultra Beasts start appearing around Alola, Hau and Hala are seen coming face to face with a BlacephalonUS/StakatakaUM at Mahalo Trail. Hala chooses to entrust the battle to his grandson, who is soon joined in the battle by Tapu Koko. After the Necrozma crisis is over and the player starts taking on Mina's trial, the player encounters Hau and his fully evolved starter at Hau'oli Cemetery, also taking on Mina's trial. He then tells the player that they should have a serious battle once they're both done with their island challenge. Later during Mina's trial, he also shows up outside the Aether House, encountering the player and Guzma there. He encourages Guzma to become something no one's ever been before, before giving the player one last warning of their upcoming serious battle. After the player has cleared Mina's trial, Hala will show up and reveal that he and Hau had finally had an all-out battle, in which Hau had managed to defeat his grandfather.
After the player has defeated the Elite Four, instead of Professor Kukui challenging them to test the player's worthiness, Hau will appear to face the player as their final challenger at the Pokémon League to determine the Alola region's first Champion. This time, Hau takes the fight much more seriously and asks the player to use all their strength. He also once again appears in the Title Defense battles, now being the strongest possible challenger.
During the post-game, Hau will accompany the player to Poni Grove to help the Ultra Recon Squad deal with a group of BlacephalonUS/StakatakaUM that have appeared there. Regardless of how the player fares against the Ultra Beasts, Hau eventually manages to catch one, giving it to the Ultra Recon Squad for research purposes.
After the Ultra Beast incident at Poni Grove has been solved, Hau can be found at Iki Town, going through the memories of his island challenge with his starter. The Z-Crystals he gave to the player in Sun and Moon are now obtained from Hala instead.
Pokémon
Hau's team slightly differs based on the player's starter Pokémon choice. He chooses the starter that is weak to the player's starter, while his Eevee evolves into the Eeveelution with a type advantage over the player's chosen starter.
Hau joins the player in three Multi Battles, two against pairs of Aether Foundation Employees and one against Faba and an Employee. In the last battle, all of his Pokémon have gained one level.
Hau debuted in No Stone Unturned!, where he and his father had just returned to Alola after a long time away. He was training with Dartrix, only for its attacks to accidentally hit Ash, Rotom, and Pikachu. Hau became excited upon seeing Ash's Z-Ring and asked if he had taken part in Hala's grand trial. Hau then had a battle against Ash, using Dartrix against Rowlet. Hau ended up winning when Ash dropped his Grassium Z. Ash suggested they have another battle, but Hau was about to have a meeting with his father, so he declined but promised to meet up the next day for a rematch. The next day, they conducted their rematch after Rowlet learned how to use Seed Bomb, but it was still not enough to defeat it. In a last-ditch effect, Ash and Rowlet performed the Z-MoveBloom Doom, which was able to defeat Dartrix.
In Battle Royal 151!, Hau competed in the Battle Royal preliminary round of the Manalo Conference with his AlolanRaichu and was able to progress to the Top 16. The match-ups revealed that he would be battling Samson Oak. In Battling Besties!, Hau went up against Samson in the first round of the Manalo Conference. He used his Raichu against Samson's Alolan Exeggutor and eventually won, advancing to the second round.
In The Battlefield of Truth and Love!, Hau approached Ash with his Decidueye upon learning that they would be battling each other in the next round of the Manalo Conference. In Imitation Is the Sincerest Form of Strategy!, Hau went to search for Ash, who was late for their battle due to his training with Rowlet. After finding him and making it to the battlefield with him, Hau and Ash began their battle. During the battle, Decidueye was able to dodge Rowlet's Bloom Doom, before using its own Z-Move, Sinister Arrow Raid, which was barely avoided by Rowlet. The battle concluded in Battling on the Wing! after Decidueye was defeated by Rowlet's Brave Bird, thus eliminating Hau from the tournament. Though he congratulated Ash for his victory, Hau was left dismayed by his loss, but he was comforted by Hala, who complimented him for the battle.
In Enter the Champion!, Hau attended the award ceremony for the Manalo Conference victor, only for it to be interrupted when a Guzzlord arrived at the stadium through an Ultra Wormhole. In the following episode, Hau helped evacuate innocent civilians to safety, only for another, ShinyGuzzlord to emerge from another wormhole at the shopping area. By combining their Z-Moves, Hau, Gladion, Kiawe, Lana, Lillie, Sophocles, and Mallow managed to successfully knock the Shiny Guzzlord back into Ultra Space.
Hau is an energetic young Trainer keen to take on the Island challenge. His inexperience showed during his debut appearance in No Stone Unturned!, where he was confident though lacked direction in his battle style. Hau's focus and ability to foresee his opponent's strategy had improved by the eve of the Manalo Conference, which enabled him to advance to the Top 8 before he was defeated by Ash in their match in Battling on the Wing!. He is still learning to cope with defeat, though quickly calms himself down. He also values the experience of others as inspiration, especially Ash and his grandfather Hala.
Pokémon
This listing is of Hau's known Pokémon in the anime:
When Ash met Hau again in League Offenders and Defenders!, Dartrix was revealed to have evolved into Decidueye. Hau later used Decidueye during the battle against Team Skull, where it went up against Rapp and her Zubat and won.
Decidueye reappeared in a flashback in Final Rivals!.
In Z-Move Showdown!, Decidueye was used to battle a ShinyGuzzlord to prevent it from the destroying the Manalo Stadium. With a combination of Z-Moves, Decidueye, among others, managed to send the Shiny Guzzlord back into its Ultra Wormhole. Decidueye was later seen watching Ash and Professor Kukui's exhibition match alongside its Trainer.
In Battling Besties!, Hau used Raichu in his match against Samson Oak and his Alolan Exeggutor. The battle ended in Hau's victory, advancing him to the second round.
In The Announcement and the Prize, Hau faced Gladion in the first round. During their battle, Gladion asked why Hau joined the tournament and assumed he wanted to surpass his grandfather Hala. When Hau replied that he thought it would be fun, Gladion called him weak and won the battle.
In A Photoshoot and the Abandoned Thrifty Megamart, Hau met Ilima at the Melemele IslandTrainers' School and requested to join him and the other Trial Captains in confronting Team Skull at their hideout in Po Town. Hau wanted to meet Guzma, who was a student of Hala's, but ended up believing that only victories mattered in battles. After Ilima accepted, Hau went off to buy malasadas, as he believed that with food, everyone might get along easier. Later that day, Hau and Ilima met with Lana, Kiawe, Mallow, and Acerola at Po Town. Their presence alerted Guzma, who demanded to know why his base was being invaded. When the Hau and the Captains revealed they only wanted to talk, Guzma agreed on the condition they made it to him first. He then summoned a Pheromosa, Celesteela, and Guzzlord; and had them attack Hau and the Captains. Despite their best efforts, Hau and the others were completely outmatched by the rampaging Ultra Beasts.
In Confusion and Monsters from Another World, Sun arrived at Po Town, only to get caught up in the commotion. Annoyed Hau and the Captains were still fighting, Guzma revealed a Cosmog and had it open more Ultra Wormholes. Gladion appeared, demanding to know where Guzma got the Cosmog and Ultra Beasts from. Revealing his true aim is to destroy Ultra Beasts, Gladion battled the beasts Guzma summoned with his Type: Null. To everyone's shock, Gladion also revealed the Aether Foundation's president, Lusamine, was the one who gave Guzma Cosmog as part of her plan to create a paradise filled with nothing but Ultra Beasts and herself. Eventually, the Ultra Beasts broke out of Po Town's barrier, allowing them to wreak havoc across Ula'ula Island.
Six months later, Hau traveled to Exeggutor Island, where the Trial Captains and island kahunas had been training in preparation to face the Ultra Beasts. Despite Hala initially refusing to let him join the others in training, Hau requested to participate in the battle to protect Alola, revealing that he had been training by himself while traveling around Alola and unknowingly obtained a Sparkling Stone, which was made into a Z-Ring by Olivia. Seeing the Z-Ring and Hau's determination, Hala agreed to train his grandson.
Hau was taken to Resolution Cave, where he sparred with Hala until his Brionne evolved into a Primarina. After finishing their training, Hala decided they should join the others on Mount Lanakila, only to be interrupted by a battle between Tapu Fini and a Buzzwole. After learning the others were also battling the Ultra Beasts, Hau and Hala teamed up to assist Tapu Fini.
Several months later, Hau decided to open a malasada and Tapu Cocoa shop. He was assisted by a reformed Guzma and received recipe tips from Mallow.
Pikachu is Hau's first known Pokémon. It was first used as a Pichu at the Iki Town festival tournament, where it battled Gladion's Porygon. Eventually, it was defeated, forcing Hau to switch for Komala. Sometime during Hau's solo training session, it evolved into a Pikachu.
Komala is Hau's second known Pokémon. It was first used at the Iki Town festival tournament to replace Pichu after it was defeated. In retaliation, Gladion sent out his Type: Null and used it to battle Komala. Eventually, Komala was defeated.
Primarina is Hau's third known Pokémon. It was first seen as a Popplio with Hau at the Melemele IslandTrainers' School. Hau received it from Professor Kukui. Sometime during Hau's solo training session, it evolved into a Brionne. It later evolved into a Primarina after his training with Hala.
