| Ash's Riolu might evolve in one of the future episodes or chapters.|
Please do not insert any speculation, nor from the confirmed synopsis until the episode or chapter in which the Pokémon evolves has aired or been released.
Upon hatching, Riolu was shown to be very determined, using Vacuum Wave on anyone it sees. It also seems very proud and independent, as it refused to be cuddled or cared for despite being a baby Pokémon. It can also be cocky and reckless, picking fights with other wild Pokémon even though it was clearly outmatched, similar to Ash's Scraggy right after hatching. Similar to Ash's Snivy and Greninja when it was a Froakie, Riolu also had great expectations for those it bonded with. At first, Riolu wasn't the most open type, as it refused to hatch without finding a Trainer with a matching Aura. Also, Riolu was distrustful towards Ash, due to not recognizing him as the one with the strong Aura it had sensed. However, Riolu changed its opinion about Ash when it not only sensed his Aura powers but also when he helped it get out of a tough spot. After that, through their Aura abilities, Riolu and Ash formed a close bond with each other, much like Greninja and their Trainer's closeness to each other through their Bond Phenomenon power.
In addition, Riolu admires Ash's courage, kindness, and determination as it shows to have warmed up to him. Also, Riolu would hold onto Ash's hand or leg as well as mimicking its Trainer's actions, much like Serena's Braixen did during her time as a Fennekin. Riolu even likes being with Ash and doesn't usually leave his side as it usually stays outside of its PokéBall, much like Ash's Rowlet and Ash's Naganadel when it was a Poipole. Through Ash's influences, Riolu has become very friendly and supportive with everyone around it as it picked up some of his traits, such as eating a lot. Also, Riolu seems to have picked up some of Pikachu's traits as well as assumed it was gonna be sent out to battle but was bummed out that Ash didn't have it participate in the battle, although it got over it and choose to cheer for its Trainer on. In addition, Riolu seems to admire its evolved form, much like Ash's Lycanroc did when he was a Rockruff. Riolu would usually train with Mimey to help its moves. However, Riolu easily became training partners with Ash's Farfetch'd for battles as well, much like Scraggy with Iris' Axew and Lycanroc with Ash's Incineroar. Also, Riolu has a habit of coming out of its Poké Ball on its own, much like Misty's Psyduck, Jessie's Wobbuffet, May's Skitty, Ash's Oshawott and Clemont's Chespin.
As an egg
Riolu was originally an egg from Sinnoh that got imported to Kanto. It was passed down from one caretaker to another, but it refused to hatch as it hadn't found a Trainer that was worthy of it. However, at the Vermillion City Pokémon Center, It sensed Ash's aura being transmitted to it during his battle with Hashiba. When it sensed Ash's presence at the Pokémon Center as he came to treat his Pikachu, it rolled towards him and Nurse Joy handed it to him. Deeming Ash worthy, Riolu finally hatched during the night.
Upon hatching, Riolu was greeted by Ash, Pikachu, Goh, and Raboot. However, out of distrust and not recognizing Ash as the person who possessed the same Aura, Riolu shot a Vacuum Wave at him then jumped out of the window and ran away from the laboratory. As Riolu left the institute, it encountered a lot of wild Pokémon as it battled them but got attacked by them and had taken a lot of damage. When Riolu encountered an Onix, it was protected by Ash and Pikachu, who were looking for it, as they notice that the Emanation Pokémon was in trouble. While watching Ash and Pikachu battle Onix, Riolu sensed the Aura within him. After realizing that Ash was the one who possessed the powerful Aura it sensed in its egg state, Riolu pushed Pikachu aside and decided to battle with him. Thanks to Ash's commands, Riolu was able to defeat Onix. At the Pokémon Center, Riolu had its wounds healed and decided to come with Ash, which he accepted, thus joining his team.
Riolu was training its Vacuum wave against Mimey's Reflect at Cerise Park before Ash was called by Goh. It joined Ash in helping take care of Goh's Pokémon but notice that their all fighting as there been a food shortage problem. After seeing that the problem was getting worse, Riolu accompanied Ash to investigate the food shortage as they decided to spend the night at Cerise Park in order to find out who's been taking the food. However, Riolu, Ash, and Pikachu all fell asleep during their shift as they woke up that next morning to find out that the bait they left out was gone. Seeing Goh's Pokémon fighting, Riolu, Pikachu, and Raboot tried to break it up but to no avail until Dragonite grabbed everyone. While watching the fighting and when Goh's Golurk went on a rampage when its seal was removed, Riolu tried to help but became stunned when its Vacuum Wave didn't do a thing as it didn't know that Fighting-Type moves didn't work on Ghost-Types. After some of Goh's Pokémon put Golurk's seal back on, Riolu helped Cascoon evolve into Dustox and became amazed to see their evolution. Riolu enjoyed some food with Pikachu, Dragonite, and Goh's Pokémon. However, while playing on Golurk, Riolu and everyone was falling off when the Automaton Pokémon went on a rampage again when its seal came off.
Riolu was later used to battle Matori and her Team Rocket Grunts in an attempt to save the captured Pokémon at the Sinnoh region's Resort Area. However, it was quickly overpowered by Team Rocket's Purugly and was initially knocked out. After Pikachu was taken by Team Rocket, Riolu was with Ash, Goh, and Raboot at the Pokémon Center until they were approached by the Team Rocket trio, who want payback against Matori, in disguise as they put a tracking device on one of the grunts Pokémon. While Goh distracted the grunts, Riolu and Ash came to Pikachu along with the other Pokémon rescue. After all of them were set free, Riolu and Pikachu teamed up with the other Pokémon as their efforts forced Team Rocket to retreat.
Riolu joined its Trainer along with the rest of the team to the Kalos region where Ash was battling in the World Coronation Series Battle festival. Sensing the presence of Aura, Riolu headed towards the source with Ash, who was sensing the same thing, accompanied it as it saw that its evolved form was emitting them. After Ash with Pikachu realized that it was Korrina's Lucario and Korrina arrived, Riolu was introduced to them as it became impressed with its evolved form. Although it wanted to battle Lucario, Riolu and Pikachu obeyed Ash as they sat in the sidelines in order to watch. Riolu was pleased to see Ash win but was more impressed to see how strong Korrina's Lucario was.
Riolu continued his training with Mr. Mime, having learned Force Palm, and managed to finally break through its Reflect. When Professor Cerise decided to surprise them with tickets to a Pokémon World Championship Match in the Galar Region, Ash decided to take Riolu with him. Upon arriving at the stadium, Ash sent out Riolu to watch the battle. Riolu watched the battle intently, watching it closely. After the match, Ash encountered a Galarian Farfetch'd, and after Goh failed to catch it, he decided to battle it himself. When Ash was originally going to choose Pikachu, Riolu showed awareness to what was happening inside of its Poké Ball and popped out of the ball on its own, showing that it wanted to battle. Ash then revealed to Goh that Riolu had also learned Double Team and Reversal. Riolu was eventually knocked to the ground after being hit by Farfetch’d’s Brutal Swing, but Ash cheered it on, and Riolu struggled back to his feet. Using a powerful Reversal hit, Riolu knocked Farfetch’d to the ground. Riolu was shocked when Ash began to cheer for Farfetch’d as well. After Farfetch’d got back up, Riolu prepared to finish it, but it ended up fainting after using the rest of its energy just to get up. Riolu then watched as Ash welcomed Farfetch’d to join his team and subsequently caught it. Riolu and Farfetch’d immediately resumed their training afterward.
That following morning, Riolu was eating some of Galar's famous Curry on Rice with its Trainer, Pikachu, Goh, Raboot and the two Farfetch'd. When the food was disappearing, it turned out to be the work of a wild Sobble. It later discovered a wild Silicobra and cheered Sobble on. Afterward, it accompanied Ash and Pikachu in the search for Sobble, only to find an Oddish in a bush. When Sobble was being held captive by Team Rocket, Riolu took part in the battle to rescue the frightened Pokémon. Riolu was later seen having a training match against Pikachu. Ash had Pikachu use Iron Tail and had Riolu use Force Palm to block it, which worked. Riolu then followed Ash and Pikachu after Goh told them that Sobble had gone missing. After finding a group of crying Pokémon, Sobble’s tears soon spread far enough to affect them, and they all began to cry as well.
Riolu eventually entered its first World Coronation Series match against Tony and his Electabuzz, with Ash and Pikachu cheering it on. Despite Electabuzz being an evolved Pokémon, it ended up defeating the former with Vacuum Wave. After the battle, Pikachu showed that he wanted to fight next, but Ash rejected him after saying that Riolu was on a roll with its training. After returning back to Cerise Park, Ash brought out his Farfetch’d to train against Riolu. This time Riolu ended up knocking it out successfully with Reversal. Ash attempted to finish the training session, to which Pikachu became excited, but Riolu wanted to keep on fighting. Goh suggested that Riolu should fight his Farfetch'd as well, much to Pikachu’s dismay. Again, Riolu managed to knock it out by using Vacuum Wave. Ash then attempted to end the training again, but Riolu quickly showed that it wanted to continue, despite being tired. Goh then brought out his Beedrill and the two kept training. The training continued all day until Delia Ketchum made a sudden appearance at the lab. Delia made food for all the Pokémon, and Riolu quickly finished it's so fast that it could get back to training with Ash.
Riolu soon did some training at the Fighting Dojo in Saffron City against both a Hitmonchan and a Hitmonlee. It later took part in the match against Bea's Grapploct, but was defeated from Liquidation. Riolu later did some jogging with Ash and Pikachu until it had partaken in two World Coronation battles where it, unfortunately, was defeated by two multi-limbed Pokémon. It later accompanied the Research fellows in investigating the mysterious sandstorm in the Hoenn Region. Upon encountering a wild Flygon, Ash switched Pikachu out for Riolu since Pikachu's Electric-type attacks were having no effect on the Mystic Pokémon. Finding it challenging to land a hit on Flygon, Riolu sensed its trainer was in distress. After Goh captured the Flygon, Riolu and Pikachu went to comfort their trainer when he decided to start from scratch. Riolu was later seen enjoying lunch with Ash's current team and Alolan team at the Pokémon School.
Riolu trains against Pikachu until Goh tells Ash that Bea is in Johto. Upon arriving, Riolu watched Pikachu take on Bea's Hitmontop in their rematch. When Grapploct came out, Riolu looked in frustration at Pikachu's next opponent. After Pikachu was knocked out due to Liquidation, it was up to Riolu to take on the Jutsu Pokémon. When it got caught in the Octolock, Riolu used its aura to boost its strength and unleashed a powerful Force Palm. After a collision of Force Palm and Close Combat, both Pokémon were knocked out, resulting in a draw.
- Riolu is Ash's first Pokémon:
- That Ash hatched from an egg since his Noivern as a Noibat.
- Also to have spent less than one episode as an egg.
- To have known a single move upon hatching.
- To be a Generation IV Pokémon since Gible.
- To be a Fighting-type since Hawlucha.
- To be a Baby Pokémon.
- That isn't a Pokémon in its fully evolved form to be obtained in Pokémon Journeys.
- That isn't a Pokémon captured by Ash in Pokémon Journeys that didn't originate from Generation I.
- That Ash hatched from an egg since his Noivern as a Noibat.
- Riolu's Pokémon Egg is somewhat similar to the 10km egg in Pokémon GO.
- Its initial usage of Vacuum Wave is similar to that of Aura Sphere.
At Oak's Lab
At Kukui's house
At Cerise Laboratory