Primal Lucario is a bipedal, jackal-like Pokémon that's around four feet in height. His forepaws are black and have one white spike on each arm on the upper-side of its wrists. In addition, there's a third spike on Primal Lucario's chest. His snout and ears have also grown longer since his evolution from Primal Riolu. Primal Lucario also has a furry yellow torso, and its thighs are in the shape of what looks like blue shorts. Also, Lucario stands on the balls of its feet, rather than on its entire foot.
Primal Lucario are sensitive to a special type of energy called Aura. Primal Lucario can study these waves to predict the movements of their opponents, and use them to track anyone. They can also guide the waves offensively to create explosive balls of Aura energy (such as Aura Sphere, one of only two non-legendaries to learn that move). Primal Lucario are also able to understand human speech; some people say that Primal Lucario can also speak it, though only one has reportedly done so, and through telepathy, along with it's counterpart.
Normal Lucario are considered to be prideful creatures, and are extremely loyal to their trainers. Normal Lucario also seem to have a natural sense of justice. However, Primal Lucario is the exact opposite, and while not evil, have a sense of devil in them. They only listen to trainers they trust greatly.
Primal Lucario usually live deep in mountains very far from people to improve their skills. Therefore, like Milotic and Togekiss, they are some of the rarest non-legendary Pokémon known, and finding a wild Primal Lucario is impossible, you need to take a Lucario to SpecialK, along with 500 Pokédollers.
Over 1,000 years ago, Lucario served Sir Aaron. Lucario was sensitive to aura, invisible vibrations that all objects, especially living things, release. This enabled him to "see" objects and living creatures and predict the actions of others even with their eyes closed. Lucario could use aura as an offensive attack in the form of Aura Sphere, in which he would amass a sphere of energy and hurl it at an opponent. Aaron taught Lucario how to refine his sensitivity to aura.
When Cameran Palace was about to be caught in the middle of a war, Aaron was on his way to the Tree of Beginning to attempt to stop the battle when he came across Lucario, who had been temporarily blinded by a group of sand-kicking Houndoom, where Aaron told him that he was never going back to the castle. Aaron intended to sacrifice himself to stop the war, but Primal Lucario jumped to the conclusion that he was abandoning the kingdom, which caused Aaron to throw his staff, sealing Primal Lucario within.
Years later, in the present time, Primal Lucario was awoken from the staff when it was held by Ash Ketchum, who has a similar aura pattern to Aaron. Primal Lucario initially mistook Ash for Aaron, and was stubborn and distrustful of humans after being sealed in the staff. Unaware of Aaron's sacrifice, Primal Lucario held a grudge toward Aaron, thinking Aaron had abandoned the castle and him. He had considered himself Aaron's servant, and he could not understand the friendship between Ash and Pikachu. However, a time flower message left by Aaron shortly before his death told Primal Lucario the truth, that Aaron considered Primal Lucario a friend, not a servant.
Once again the Tree of Beginning was disturbed, threatening to destroy the balance between Pokémon and nature. Ash and Primal Lucario rushed to its core and began to use their aura to energize the tree's defense system. Using up their aura would have meant the same fate as Aaron—death. However, just as Ash was about to use up his aura, Primal Lucario pushed him away, instead sacrificing only himself to the tree.
After Primal Lucario's death, the portrait of Aaron in Cameran Palace was altered to include Primal Lucario by Aaron's side, cementing their relationship as best friends and partners in aura manipulation. Primal Lucario is later seen with Aaron once again and gives him a bar of chocolate, which he enjoys; this is surely after his death, as Primal Lucario did not know what chocolate was until Max gave it to him in an effort to earn his trust for the sake of the group.
This Lucario debuted in Steeling Peace of Mind! at Iron Island. When Ash and his friends traveled there after being contacted by Barry, they found the local Steel-type Pokémon fighting brutally against each other and the other Pokémon on the island. When a crazed Aggron attacked Ash, Riley stepped in and had Primal Lucario attack it with Close Combat. Despite being a Steel-type as well, Lucario wasn't affected like the others of its type due to its strong aura.
Riley informed Ash that, like his Primal Lucario, he could use Aura. Together they found the source of the problem: a machine operated under Mars's command that was using the Spear Key to create low frequency waves which tortured the Steel-type Pokémon. Lucario attempted to read the Aura coming out of the machine, but at that time, Mars placed the Spear Key into a pillar at the ruins the squadron was excavating. The beam that launched out of the pillar's tip overwhelmed Lucario and caused it to rebel against Riley, even breaking its Poké Ball in half when he tried to recall it.
Even then, however, Primal Lucario wasn't completely under the machine's influence and tried to destroy the machine but couldn't do it. Ash managed to finish the job and destroy the machine and Primal Lucario and the other Steel-types were brought back to their senses. When Mars realized her plan was shot, she fled and attempted to blow up Iron Island with bombs, but her efforts were thwarted when both Riley and Lucario used their combined Aura powers to contain the blast and send it flying.
Primal Lucario is a playable character available in Super Smash Bros. Brawl. It is unlocked by encountering it in The Subspace Emissary either from choosing it to battle and claim victory over Meta Knight or vice-versa. It can also be unlocked by playing 100 brawls or beating Target Smash!! on all difficulty levels (in either 1 or 2-player modes).
Primal Lucario appears to be able to talk with the help of Aura; most notably seen while using his Final Smash when it says "Watch the power of Aura!" Primal Lucario's fighting style revolves around Aura manipulation and the concept of "high risk, high return"; the more damage he has taken, the stronger it and its attacks become. Its power is at its peak when it has taken 200% damage, and is in last place during a fight.
Mei Ling:"I guess you could call it his life force. Primal Lucario can use his own Aura and turn it into power. Every time Primal Lucario's damage increases, his Aura gains strength, making his attacks more powerful. So don't think you've got him beat just because his health is down."
Solid Snake:"The cornered rat will bite the cat... Sounds like trouble."
Mei Ling:"Hey! When did you become so good with proverbs?!"
Solid Snake:"You must have rubbed off on me."
Mei Ling:"Well, come back in one piece, and I'll teach you all the Chinese proverbs you can handle."
Primal Lucario's Final Smash. After flying off the screen, Primal Lucario reappears in its center. It then launches a powerful Aura attack against all foes within a certain distance. The key to this attack is the ability to change its angle--it's a must to sweep slowly left and right to his selected enemies multiple times. The last blow will send the victim flying away.
This Pokémon was unavailable prior to Generation IV.
Lucario appears to be based on the Egyptian god Anubis, who has the head of a jackal. It also seems to be based on an Egyptian boxer. Boxing is a sport that is believed to have origins in Egypt. The black appendages on the back of its head are used to detect the Auras of creatures and objects around it. While Lucario reads Aura, it closes its eyes, and thus the appendages and the way they look "tied" around its face appear to be based on someone being blindfolded.
Primal Lucario's name possibly derives from part of a Japanese spelling of oracle or orichalcum in reverse, reflecting its mythical design, its ability to see into the supernatural, and its Steel-type. It may also refer to Cairo, Egypt. The word pharaoh may also be involved. The Primal part of it's name is because it has gone "Out of Control".