After entering the forest, Ash and Pikachu walk towards the middle of the forest while conversing.
"(So where going to train my unique ability, right)?" Pikachu asked hopingly.
"Yeah, I feel that we will need it in the near future." Ash answered
"(Finally, we had been trying to hide that for years. I will finally be able to use it in a battle)." Pikachu exclaim happily.
"Not until we master it. The last time you accidently us it, you devastated a herd of Tauros." Ash stated as he remember how his buddy destroyed the area and how he injured all those Tauros while using his secret ability.
"(Hey they attack us and you didn't have any Pokémon then because we were headed to Hoenn for the first time. If I didn't use it we would have been dead. You weren't exactly an Aura Prince back then)." Pikachu retorted.
"I know that, but I need you to control that power if we will ever use it in a Pokémon battle. I don't want other Pokémons getting accidently killed when you lost control over that ability." Ash said while looking at his partner.
Pikachu sigh, "(Yeah, I know that)." Pikachu sigh.
Looking at his Pikachu, Ash could tell that he was depressed. He knew that his Pikachu was disappointed that he has a powerful and unique ability but could not use it because of his lack of control. He knew that feeling because when he first trained (secretly) with his aura, his Aura Spheres always blow up in his face. He didn't even believe it himself when Arceus herself appeared before him and gave him the title Aura prince, the highest title for an Aura Guardian, considering how pathetic he was when he began his training. "Don't worry buddy, just remember how I became an Aura Prince, I was pathetic at first but here I am the youngest Aura Prince in the history." Ash said trying to boost Pikachu's morals.
That works because Pikachu began laughing hysterically. "(Yeah I remember that. Sir Aaron's Lucario always compliment you for having such a powerful aura but always scolded you because you lack control. He even beat you down once when your Aura Sphere exploded in both of your faces)." Pikachu said between his laughs.
Ash merely grunted while remembering how he became an Aura Guardian. It was during his travel to the Battle Frontier when they visited Cameran Palace (From the movie Lucario and the Mystery of Mew). It was suppose to be a normal visit until he, after winning the Pokémon competition there, awaken an old Lucario that was sealed in a staff. His life greatly changes after that.
When they were travelling tpwards the Tree of Beginning to save his Pikachu, Pikachu was 'kidnap' by Mew, (Sir Aaron's) Lucario approach him the very first night of their journey to the tree. He literally force him to train to become an Aura Guardian, he was against of it at first but after a barrage of Aura Spheres he was force to accept the Lucario's training. It turns out that he was a fast learner in becoming an Aura Guardian, he was able to grasp the basic of Aura in less than two days. His only problem was manipulating his Aura in a form of an attack, he had no problem in forming barriers with his Aura but he absolutely suck in using it in an attack, the reason was because his Aura was so powerful that it was hard to control that it would most likely blow-up on his face. He was able to overcome it after much practice and beating from his teacher but that was the last thing (Sir Aaron's) Lucario had thought him but before he 'died' he manage to gave him a Time flower which contains all the things he needs to complete his training. He trained using that time flower as his guide until he became an Aura Prince.