Lucario is Korrina's primary Pokémon which has ability to Mega Evolve. It made its debut in Mega Revelations!. Lucario and Korrina have known each other for a very long time since it was a Riolu and have been very best friends. During their travels with Ash and his friends, Korrina and Lucario's main goal was to find a mega stone called the Lucarionite and doing so learn to understand the importance of Mega Evolution. When they travel to the cave of trials, they encountered a Blaziken and battled it. Just as they were about to finish the battle, Korrina's grandfather, Gurkinn arrived revealing that Blaziken is his Pokémon.
Gurkinn was truly impressed with Korrina's determination and felt that she and Lucario passed the test. As a reward for all their hard work, Gurkinn gave Korrina the Lucarionite so she will Mega Evolve her Lucario. After Lucario was successfully Mega Evolved, Korrina engaged Ash and his Pikachu to a battle. Both of them battle finely, but unfortunately for Korrina, something was going terribly wrong with her Lucario when it was battling Pikachu. During the battle, Lucario lost complete control of itself and started to go on a violent rampage. Korrina tried to make Lucario stop, but it kept on attacking Pikachu without listening to her commands. Just as Lucario was about to kill Ash and Pikachu with a really strong Power-Up Punch attack, Gurkinn sent out his own Lucario to put a stop to the rampage. After that, Lucario returned to its normal form and was taken to the Pokémon Center.
After Lucario and Pikachu were healed, Gurkinn engaged his granddaughter in a battle so he can show her why her Lucario lost complete control of itself when Mega Evolved. However, Lucario went on a rampage once again and lost. Korrina was so confused about why Lucario can't control itself when Mega Evolved, but Gurkinn tells her it is because of her lack of understanding Mega Evolution and Lucario's uncontrolled arrogance. Gurkinn ordered both Lucario and Korrina to travel to the Pomace Mountain where she will train with another Mega Evolution expert named Mabel, who he was taught from when he was a young boy. Korrina obeyed her grandfather's command and Ash and his friends went with her as well.
When they arrived at the Pomace Mountain, Mabel and Korrina engaged in a battle with her Mawile, which can also Mega Evolve. But Lucario lost control of itself again and lost. Mabel then decides to have Korrina and Lucario help her arrange a lot of flowers with her, which Korrina accepted. But after several days of flower arranging, Korrina got so confused to why she wouldn't give her the special training like she asked Mabel to. But Mabel told her that the flower arranging was in fact the training all along. Mabel told her that flower arranging was to strengthen the bond with Lucario and Korrina. All of a sudden, Team Rocket appeared and took Pikachu and Mawile. In rescuing the Pokémon, Korrina once again Mega Evolved her Lucario, but lost complete control again. Following Mabel's advice, Korrina managed convince Lucario to remember what all of their training was for and both of their hearts are one. In the process, Lucario finally gained control of itself and its anger ceased. Lucario then rescued Mawile and Pikachu and learned Aura Sphere to send Team Rocket blasting off. The next day, Korrina and Lucario bid farewell to Ash and his friends and will be looking forward to their gym battle with each other sometime.
Sometime later, Korrina used her Lucario as her third and last Pokémon during the Gym Battle with Ash in its Mega Evolved form. With its intense strength and power, it managed to defeat Ash's Fletchinder and Hawlucha. But when it went up against Pikachu, the two Pokémon seemed to be evenly matched. After a hard but long battle, Pikachu was able to defeat Lucario and win the match for Ash, thus winning him his third Kalos Badge, the Rumble Badge. After the intensive Gym Battle, Ash and Korrina agreed to battle again someday.
|Swords Dance||Mega Revelations!|
|Bone Rush +||Mega Revelations!|
|Power-Up Punch +||Mega Revelations!|
|Metal Sound +||The Cave of Trials!|
|Aura Sphere +||The Bonds of Mega Evolution!|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.