Under Professor Kukui's care
Lycanroc, as a Rockruff, was a wild Pokémon that one day stumbled across Professor Kukui's house. It was starving and left confused from another Pokémon's Teeter Dance. Professor Kukui gave it some Pokémon food, which made Rockruff decide to stay at Kukui's house. From then on, Rockruff lived with Kukui, although he never caught it in a Poké Ball.
Rockruff first appeared in The Guardian's Challenge!, where it had dinner and played with Ash and Pikachu. It was later seen the following day with Professor Kukui, watching the welcoming party Ash's classmates had prepared for him. Kukui had planned to battle Ash and Pikachu with Rockruff, but the party was interrupted by Tapu Koko, who challenged Ash to a battle instead.
In Rocking Clawmark Hill!, Rockruff came home injured, causing Ash and Professor Kukui to investigate the reason behind its injuries. This led them to Clawmark Hill, where they discovered that Rockruff had been fighting with other wild Pokémon, including a Magmar. With Ash's help, Rockruff was able to master Rock Throw, which helped it defeat Magmar. At the end of the episode, Professor Kukui encouraged Ash to catch Rockruff after seeing the bond the two had developed.
In A Guardian Rematch!, Lycanroc, as a Rockruff, was used in its first official battle, in which it faced Hiroki and his Mudbray. During the battle, Rockruff performed Breakneck Blitz for the first time, which was able to defeat Mudbray.
In A Glaring Rivalry!, Rockruff was seen training with Ash's Rowlet and Litten. Later, it witnessed its evolved form Lycanroc winning a battle against a Blastoise, which greatly impressed it. Ash later used Rockruff in his battle against Gladion in which it battled Lycanroc. Rockruff got quickly overwhelmed by Lycanroc's great speed and fierce moves, but was still able to battle. The battle was then interrupted by Team Rocket, who captured Pikachu and Lycanroc.
In Trials and Determinations!, Rockruff was used in the Akala Island grand trial alongside Rowlet, battling Olivia's Lycanroc and Probopass. Despite their opponents giving them tough times with their combination tactics, Rowlet eventually managed to defeat Probopass with Bloom Doom. Unfortunately, Rockruff, who was acting aggressively, was so desperate to battle Lycanroc by itself that it impulsively used Bite against Rowlet, accidentally knocking it out. Despite this setback, Ash encouraged Rockruff to use its fighting spirit, allowing it to outspeed and defeat Lycanroc, earning Ash a Rockium Z. Professor Kukui and Olivia then revealed to Ash that Rockruff's behavior was a sign that it was going to evolve soon.
In Rising from the Ruins!, Rockruff went off by itself to train after remembering the aggression it demonstrated during Olivia's grand trial. While training, it encountered Tapu Lele, who challenged it to a battle. Rockruff was no match for the guardian deity, however, and was easily beaten. When Ash found Rockruff, he tried to stop it from running away again, but failed. The next day, Rockruff was walking on a cliffside when it got startled by a Fearow, causing it to fall down into a river. The injured Puppy Pokémon was later found by Olivia and Gladion's Lycanroc, who brought it to the Ruins of Life, where Tapu Lele resided. When Ash, Professor Kukui, and Olivia arrived at the ruins, Tapu Lele used Draining Kiss to drain Ash and the two Lycanroc's energy, which it then used to heal Rockruff's wounds. Afterwards, Rockruff went to the edge of a cliff and began to howl as the setting sun turned green. It then evolved into Dusk Form Lycanroc, after which it got happily embraced by its Trainer and the rest of Ash's party.
In Mimikyu Unmasked!, Ash had Lycanroc use Continental Crush against Team Rocket, but the attack failed. After another attempt, Professor Kukui gave him some advice, which led to Ash training with Kiawe and his Turtonator. When Team Rocket showed up again and Jessie challenged Ash to a battle with her Mimikyu, Lycanroc mastered Continental Crush and sent Team Rocket blasting off, much to their surprise.
Lycanroc going berserk after discovering its fur is dirty
In A Masked Warning!, Ash discovered while washing Lycanroc that it was so proud of its appearance that it would fly into a rage and attack if its fur got dirty. Lycanroc attacked Litten and Litten fought back, with Ash placing himself between his two errant Pokémon. This helped Lycanroc to calm down, and it was very apologetic towards Ash. Later, Ash used Lycanroc to battle Gladion's Type: Null, nicknamed Silvally, where it was outmatched by its opponent sheer power. During the battle Lycanroc was thrown into a nearby lake which drenched its fur, causing another rage during which it refused to listen to Ash's commands. Despite this, Silvally was still the stronger opponent and Lycanroc was easily held at bay before it could regain control of itself. After Lycanroc recovered, Ash and Gladion decided to continue the battle, but despite its best efforts, Lycanroc couldn't stand up to the power of Silvally's Crush Claw and was defeated.
In Rescuing the Unwilling!, Lycanroc fought alongside Lillie's Vulpix, Snowy, against Lusamine's Clefable, which was under Nihilego's control. It saved Lillie from Clefable's Moonblast with an Accelerock. After Lycanroc knocked back Clefable with a Rock Throw, Lillie reminded Clefable of the Clefairy doll they used to play with together, in order to free it from Nihilego's command. When Clefable began powering up a move, Lillie gestured Lycanroc and Snowy not to attack before freeing Clefable with a simple embrace.
In Tough Guy Trials!, Lycanroc was used to battle Nanu, going up against his Krookodile. During the battle, Nanu had Krookodile deliberately anger Lycanroc, even going so far as to make it go berserk by dirtying its fur with Mud-Slap. Despite the furious attacks in its angered state, Lycanroc was defeated after Krookodile used Counter to send it flying before finishing it off with Crunch. Afterwards, at Acerola's library, Lycanroc sulked over its defeat. It was cheered up after Ash asked Acerola to help him find a place where he could train for a rematch with Nanu.
In Some Kind of Laziness!, Acerola took Ash to see Tapu Bulu at the Ruins of Abundance so it could help him train. After some time, the duo managed to meet with Tapu Bulu and convince it to help them. At one point during their stay, it began raining, so Tapu Bulu decided to knock Lycanroc into a nearby pond, dirtying its fur and making it go berserk. By reminding Lycanroc of its time as a Rockruff and the bond they share, Ash finally managed to calm Lycanroc down. Impressed by this act, Tapu Bulu decided to battle Lycanroc. Though Tapu Bulu proved to be a powerful opponent, Lycanroc learned Stone Edge during the battle, after which Tapu Bulu called the battle off.
In Guiding an Awakening!, Ash faced Nanu in a grand trial battle, but was only allowed to use Lycanroc against all three of Nanu's Pokémon. After managing to defeat Nanu's Krookodile and Sableye, it went up against Nanu's Alolan Persian. Throughout the battle, Nanu used his previous strategy of angering Lycanroc so that it would go into its red-eyed state. Ash, worried that Lycanroc could go berserk again, kept telling it to keep calm throughout the battle. Nanu, realizing the truth of the situation, decided to anger Ash himself by mocking his skill as a Trainer. In order to calm its Trainer down, Lycanroc chose to tackle Ash, revealing that it was in complete control of itself the entire time. Realizing that he let his anger and frustration from Nanu's insults go to his head, Ash apologized to Lycanroc and continued the battle. After an exchange of Z-Moves with Persian as well as its newly learned Counter, Lycanroc won the battle, allowing Ash to win a Lycanium Z.
In Twirling with a Bang!, while on the group's third Ultra Guardians mission, Ash decided to use Lycanroc's new Z-Move to weaken the Ultra Beasts they were facing, Blacephalon and Xurkitree, while they were distracted by the performance provided by the group's other Pokémon. After the successfully executed Splintered Stormshards had left the two Ultra Beasts momentarily vulnerable, Lana and Lillie were able to catch them and thus complete the mission.
In Securing the Future!, Lycanroc joined the rest of Alola in showering Necrozma with light so it could return to its normal form.
In Showdown on Poni Island!, Ash used Lycanroc during his battle against Gladion and his own Lycanroc. Gladion's Lycanroc was able to withstand Splintered Stormshards before defeating Ash's Lycanroc with Devastating Drake.
Lycanroc in full control of its red-eyed state
Lycanroc is normally a playful, affectionate Pokémon that gets along well with both Ash and its previous caretaker, Professor Kukui. The first night Ash stayed with the Professor, Rockruff, Pikachu, and Ash were quickly able to befriend each other. As a Rockruff, like other members of its species, it likes to greet and show affection to others by rubbing up against them with the rocks on its neck, although it doesn't seem to be aware that it stings the recipient. Its affectionate personality was also shown in Now You See Them, Now You Don't!, where, despite the fact that Litten was angry toward it whilst eating and whilst relaxing at home, it continued to eat and smiled back at Litten respectively. Lycanroc appears to take its failures rather personally. As a Rockruff in Trials and Determinations!, after knocking out Rowlet in a fit of anger, it immediately came to its senses and regretted what it had done, and, despite ultimately winning against Olivia, was still visibly upset in the next episode. At the end of Tough Guy Trials!, Lycanroc was seen sulking in the corner of Acerola's house after losing its battle with Nanu's Krookodile, prompting Ash to give it a pep talk.
Although Rockruff lived with Professor Kukui before being caught by Ash, it was actually a wild Pokémon that Professor Kukui was taking care of. When Ash revealed this to his classmates at the Pokémon School, Rotom added that Rockruff readily bond with humans even if they are not captured by a Trainer. After evolving, Lycanroc started taking great pride in its fur, as shown in A Masked Warning!, and is shown to enjoy being groomed and taking baths despite being a Rock-type, as observed by Rotom. However, if angered enough, such as when its fur gets dirty, Lycanroc's eyes turned red, and it would fly into a rage, lashing out at whomever it thought was responsible. When this happened, Lycanroc became disobedient and ignored Ash's commands. This weakness caused problems later during Ash's battle with Gladion and Silvally, and was later the cause of its defeat at the hands of Nanu and his Krookodile in Tough Guy Trials!. In Some Kind of Laziness!, Lycanroc was able to overcome this destructive habit with the help of Ash and the bond the two shared, remembering a memory it had when it played in the mud happily with Ash and Pikachu when it was still a Rockruff. After this, Lycanroc no longer goes berserk when its fur is dirtied, as seen in A Battle Hand-Off!, where it got a bit of mud on its face and only reacted with disappointment. In Guiding an Awakening!, Lycanroc was revealed to have gained full control of its red-eyed state, allowing it to use it as a boost of power.
Lycanroc has a strong sense of smell as a Rockruff, which has been used to help find Rowlet and Popplio, Ash's missing Electrium Z and DJ Leo's Dugtrio. In the Poké Problem segment of A Masked Warning!, it is revealed that Ash and Pikachu had to rely on Lycanroc's nose to guide them back from Ten Carat Hill after Nebby had fallen asleep. In Night of a Thousand Poses! and Mission: Total Recall!, Lycanroc is shown to spar with Litten on occasion, even when it is separated from its Trainer.