“Watch the power of Aura!”
Lucario is a Fighting/Steel-type Pokémon from the Pokémon series. While most Pokémon in the Smash Bros. series are indeterminately gendered, this one is confirmed to be male, as shown via Solid Snake's codec, and from the description of one Event Match (The Aura Is With Me). He is from the fourth Generation Pokémon games: Diamond, Pearl, and Platinum versions, and is the evolved form of Riolu. He is appropriately classified in the Pokédex as an Aura Pokémon in these games.
Lucario appears as a playable character in Super Smash Bros. Brawl. He shares similar moves to that of Mewtwo from Super Smash Bros. Melee. He uses his many Aura attacks, and has the ability to stick to walls. Lucario has a special ability no other character in Brawl has - the more damage Lucario takes, the more damage and knockback all his attacks cause. He reaches full power at 182% damage. A move that normally does 15% damage raises to 26% damage when he is at 182%, and knocks the opponent back about twice as far as normal. Of course, not all of Lucario's moves are aura-based attacks; the dash attack and backward throw do not involve Lucario's aura.
 Role in the Subspace Emissary
Lucario is encountered at the top of The Glacial Peak which the Ice Climbers and Meta Knight climb. At the top of the mountain, Meta Knight meets Lucario. Lucario and Meta Knight pause and go into attack position, and fight, while the Ice Climbers watch, frightened. The player has the choice to play as either Lucario or Meta Knight; whoever loses the battle gets turned into a trophy, and the winner decides to revive the loser of the match.
After the loser is revived, Meta Knight and Lucario pause, as if they are about to fight each other, with the Ice Climbers still frightened. However, Meta Knight and Lucario then shake hands, which is a sign that they are now allies. The Ice Climbers are glad to see Lucario and Meta Knight teaming up. However, then, the four of them see the Halberd and the Great Fox. The Halberd is holding onto the Great Fox with its extendable claw, and it pushes the ship into the mountain to damage it. The Ice Climbers lose their balance and fall off the mountain, but Lucario and Meta Knight are able to climb on top of the Great Fox and then jump onto the Halberd, and they go inside.
The two travel through the Halberd, until Lucario notices the Cardboard Box sitting behind a piece of machinery. Using his Aura, Lucario senses Solid Snake inside, and lifts the box up. Snake prepares to fight, and Meta Knight draws his sword, but Lucario puts up a paw to stop Meta Knight from attacking, then puts another up to Snake. He then turns and sees a bright red Aura next to Meta Knight's, and sees the Primids coming. Lucario's eyes turn back to normal, and he, Meta Knight, and Snake start to fight the Primids. They continue, and come to a room where Princess Peach and Zelda's trophies are being kept in cages. Shadow bugs come down from the ceiling, and two dark princesses are formed. Lucario, Snake, and Meta Knight fight and defeat them.
After defeating the Dark Beings, Meta Knight slices the cages down, and Peach and Zelda are revived. Peach and Zelda look at Snake, but he and the others tell the princesses to stay. However, after they leave, Zelda turns herself into Sheik and opens the door. Peach comes after Sheik, smiling. Lucario, Meta Knight, and Snake continue with their quest, until they finally reach the Control Room, which is filled with Mr. Game & Watch men. Snake kicks the Game & Watches out the window, and the Game & Watch people all turn into Shadow Bugs.
The bugs then turn into Duon. Snake and Lucario jump out the window and meet up with Fox, Peach, Zelda, and Falco, where they fight Duon, while Meta Knight stays in the Control Room. After Duon is defeated, all the Shadow Bugs turn into the Mr. Game & Watch Trophy. Fox aims at it with his Blaster, but Peach walks to it and revives the Trophy. Mr. Game & Watch looks around, then Peach gives him her parasol. Mr. Game & Watch seems to like it. Finally Meta Knight grabs the wheel of the Halberd and controls it.
After the Falcon Flyer and the Halberd reunite, they then travel to the desert where everyone reunites. Then they fight against Ganondorf's and Bowser's ship and make it to Subspace. There in Subspace, Lucario and everyone else fought against Tabuu, but are turned into trophies. Lucario and the others are eventually revived, got through the Great Maze, and defeated Tabuu once and for all.
 Lucario's Special Moves
 Aura Sphere
Aura Sphere is Lucario's standard special move in Super Smash Bros. Brawl. It is similar to Mewtwo's Shadow Ball attack used in Super Smash Bros. Melee, but differs slightly in effect and appearance. Lucario charges up a ball of energy when the attack button is pressed, and then releases it again if the attack button is pressed again. Lucario can also stop charging at any point by moving to the side, using this as a way of escaping attack while still keeping the Aura charge. Upon fire, the Aura Sphere ball moves straight forward along the stage at random speed. The damage done and the speed of the ball is affected by Lucario's damage percent. Aura Sphere can also be used by Kirby after he copies Lucario's powers.
 Force Palm
Force Palm is the name of Lucario's side special move in Super Smash Bros. Brawl. It can be compared to Mewtwo's Confusion attack from Super Smash Bros. Melee to a certain extent. The effect of the attack changes depending on how close Lucario is to the opponent. If he attacks from a distance, he fires a short Aura wave at the opponent, knocking the foe off their feet. At close-range, he will use a much more powerful charge of Aura, and hit the opponent directly with it. The power of the attack increases accordingly to the damage Lucario has taken. However, if Lucario's size is too big, the opponent will break free from the attack before the blow is even delivered.
In the Pokémon series titles, Force Palm damages opponents, along with the possible chance of paralyzing them as well.
ExtremeSpeed is Lucario's up special move in the game Super Smash Bros. Brawl. It is more of a recovery move than an offensive one, as when used, it has no effect on a foe's damage percent. When used, Lucario will launch high in the air. The move can be aimed while shooting up, making either a sharp curve to the right or to the left. This is useful for getting back on the stage and helps stick to walls, as Lucario is capable of doing wall-jumping.
ExtremeSpeed is similar to Pikachu's Quick Attack. However, Quick Attack actually does damage opponents. This is quite ironic, since in the Pokémon games, ExtremeSpeed is much stronger than Quick Attack.
 Double Team
Double Team is the down special move of Lucario in Super Smash Bros. Brawl, acting similarly to Marth and Ike's Counter attack. When the attack is used, Lucario will stand on one leg, and split into two copies of himself. This, however, will not do any damage unless an opposing player happens to attack him shortly after Lucario uses this move. If an opponent attacks Lucario the instant or shortly after Lucario uses Double Team, Lucario will disappear, reappear behind the attacker, and slide kick into him/her, countering the move. However, it only works if the attack is used just before being attacked, as it will not work if kept in action for too long. The power of the counter attack is increased, according to the damage Lucario has taken.
In the Pokémon games, Double Team is not an offensive move. Instead, it increases the Pokémon's evasion, making it harder for opposing Pokémon to hit it.
 Aura Storm
Aura Storm is Lucario's Final Smash move in Super Smash Bros. Brawl. Once the Smash Ball is broken open, Lucario will begin to glow and rise into the air. He will then fire a powerful blast of Aura in a straight line on the stage, which goes through walls and objects. The attack will continue to devastate any player who happens to even come close to the beam, dealing heavy damage on those caught in it. The ray can be aimed using the Control Stick, allowing Lucario to catch his opponents easier. The attack lasts for about 5 seconds, before finally ending, sending a minor explosion that launches players into the air. At full power, it deals 78% damage and is a one-hit KO against most characters.
Like all other Aura-based attacks, this move will deal more damage if Lucario's damage is high.
 Solid Snake Codec Conversation
 Trophy Information from Super Smash Bros. Brawl
 Super Smash Bros. Brawl Sticker Information
All quotations are from Super Smash Bros. Brawl.