Riolu's Egg was originally found in the Sinnohregion. Despite being passed from one Day Care worker to another for a long time, it seemed unwilling to hatch. Eventually, the Egg made its way to the Kanto region, coming under the care of the Nurse Joy working in Vermilion City.
While Ash battled Hashiba, the Egg sensed the strong Aura emitted by the former and reacted to it. Ash also felt the Egg calling for him. While Pikachu was being treated at the Pokémon Center, Ash followed the call to the room where the Egg was being kept. When the Egg reacted to Ash's presence by rolling towards him, Nurse Joy decided to entrust its care to him.
The following night, the Egg hatched into a Riolu. As Ash wasn't exuding the same Aura as he had earlier, Riolu didn't recognize him and instantly fled from the Cerise Laboratory and started attacking various wild Pokémon, although all of them were too strong for it. Ash finally caught up to Riolu as it was getting attacked by an Onix. During the battle against the Rock Snake Pokémon, Riolu recognized Ash's Aura as the same one it had sensed earlier. With both Pikachu and Riolu attacking Onix, Ash was soon able to drive it away, and then, he took Riolu to the Pokémon Center to be healed. After Nurse Joy treated Riolu, it expressed willingness to be caught by Ash, which he agreed to.
In JN025, when Ash traveled to Shalour City to participate in a Battle Festival to raise his World Coronation Series rank, Riolu sensed the Aura emanating from Korrina's Lucario and led Ash and his other Pokémon to it. Korrina took a liking to Riolu and encouraged it to become stronger with Ash. Riolu instantly started admiring to Korrina's Lucario, and it came to the point that when Ash was about to start his battle with Korrina in the Battle Festival, it showed eagerness to battle, but Ash decided to go with his more experienced Pokémon. During and after the battle, even though Lucario had been defeated, Riolu still showed great admiration towards its evolved form.
In JN027, Riolu emerged from its Poké Ball to battle against a GalarianFarfetch'd. Thanks to all the training Ash had done with Riolu, it was able to defeat the Farfetch'd, which later joined Ash's team.
Personality and characteristics
Riolu and Ash
Riolu, like every other member of its species, responds to Aura, and, as such, it developed a subconscious connection to Ash before it even hatched. After hatching, it displayed a very headstrong personality, attacking wild Pokémon and even Ash, as if it had something to prove. Despite being a baby Pokémon, it harbors a dislike towards being cared for and generally seems very independent. At the same time, it appears to respect Ash as a Trainer, and can be seen following him and Pikachu around Cerise Laboratory, in contrast to the other Pokémon Ash has caught in Pokémon Journeys: The Series, who generally wander around and do their own thing.
