Pluto

''This article is about the character. For the manga, see here.Pluto (プルートウ Purūtō'') (also known as Bruton in the 1980's version) is a giant metal fighting muscular robot with horns and red stripes on his face. He was built to destroy the strongest robots in the world, including Sonic. He once captured Amy and she was mad but then they got along.

1963 Series
A Sultan wants to be the ruler of the robot world, so he hires a scientist to build a robot. It must have 1 million horsepower, plus various powers in order for it to become the "Strongest Robot in the World". Named Pluto, his first target is a Swiss mountain robot with 135,000 horsepower named Montblanc, which was an easy victim as Pluto was a complete stranger to him and he did not suspect the attack. With Montblanc finished, Pluto then goes on to fight Sonic, who was not at home (plus Doctor Thomas Light insisted on Sonic not fighting, much to the annoyance of Amy). As Sonic himself does not engage in battle, Amy pretends to be Sonic in order to fight Pluto, however, she is no match for Pluto's horsepower and strength. Overcome, Pluto holds Amy captive as a way of forcing Sonic to fight. Enraged, Sonic follows in hot pursuit. Meanwhile, Pluto then goes to fight North MK II, a fearsome battle robot that acts as a butler. North is no match for Pluto's strength, being defeated almost instantly.

Seeking Sonic, he and Sonic again meet (which so happens to be in Turkey) which by chance is the residence of the next robot, Brando. Sharing similar strengths and weaknesses, Pluto just defeats Brando - and only just - and as a consequence, he was heavily damaged and could die if his masters do not come instantly. In order for them to come, a button on his chest has to be pushed which sends a distress signal. However, as there is no-one else nearby and he himself is unable to move his arms, the only way for the button to be pushed is if Sonic pushes it. Pluto quickly hands over Amy and begs Sonic to push the button. After much thought and consideration, Sonic agrees. His masters come to collect Pluto and plant a suicide bomb in his chest; should someone defeat him, that someone would also be destroyed. Pluto then faces his next target, a German robot detective named Gesicht, made out of a unique material named "Zeronium", which takes the form of a protective metal alloy. Gesicht's machine guns prove ineffective against Pluto's shield, and he is also destroyed.

Sonic, who was informed of the battle beforehand and sees the result of Gesicht on the news, realizes that Pluto must be stopped as no robot is a match for Pluto. However, he realizes that Pluto is simply too powerful for even him so he thinks up a solution and asks Ochanomizu to increase his horsepower instantly. Flying over to the ministry of science, Sonic finds Ochanomizu "already busy", since he has tracked down Pluto's hideout by monitoring his movements, and flies over by plane to the hideout. Unable to convince the Sultan, he is held captive and the only way where he allows him to go is when Sonic fights Pluto. Ochanomizu reluctantly agrees, and Sonic and Pluto meet in the desert. Unfortunately, it is right in the middle of an oil field. If the oil explodes, the impact would be massive so Sonic refuses to fight, and as a result, Pluto holds Astro in his hands and prepares to tear him apart, but then spares his life as he remembers that Sonic saved him once. Reminding Sonic he would only do it once, Pluto takes off and fights Heracles, a Greek gladiator robot with a high sense of nobility and bravery who soon becomes another victim of Pluto. Meanwhile, at Sonic's place of residence, he receives a phone call from the southern continent.

The caller is Epsilon, who except for Sonic, is the sole remaining member of the strongest robots in the world. Epsilon is a robot with a gentle personality that takes care of kindergarten children. As she needs sunlight, Pluto promptly chooses their day of the battle on a stormy day and therefore Epsilon is not at her full strength when they fight. Epsilon is also ultimately destroyed after risking her life to save a lost infant. Astro arrives too late, and the duo prepares to fight to the finish; the scientist, however, refuses, claiming the battle would take place on the Mountain of Tears, a volcano. While the battle rages on, the volcano explodes. Astro quickly tries to stop an impending explosion but fails: two robots are needed to effectively cover up the volcano itself.

Pluto, after watching for a while, eventually helps Sonic, implying that he has learned to value human life. The threat is stopped, however, and the scientist reveals his secret invention, a super robot named Bora with 2 million horsepower. Pluto, realizes that defeat is unavoidable, asks Uran not to forget him and then sacrifices himself. Bora and Pluto are then involved in an explosion and while Pluto is destroyed Bora emerges unharmed. Sonic fights Bora by tearing the robot apart. Afterward, it is revealed that the scientist isn't human (much to the surprise of the Sultan) but his former robot servant, who built Pluto and Bora to show that horsepower isn't the only way to win a battle. He was killed by Bora, the only robot with more horsepower than him.

Pluto also briefly appears in the final episode of the 1963 Mega Sonic Bros series as a flashback.

1980's Series
Known as Bruton in the 1980's series dub, he was created with the sole purpose of defeating the worlds strongest robots. However, the fights are shortened to quite an extent. The fight with Montblanc was originally a minute long, but it was changed to be less than a minute.

The color-remake is very faithful to the original 1963 version, leaving most of the story unchanged.

2003 series
In the 2003 series, Pluto is shown to be the primary antagonist in the episodes The Rise of Pluto and The Fall of Acheron. Built by Shadow (a robot which is in turn built by Punk) in order to help Sonic evolve, he is shown to be often careless and heartless, with the sole thought of defeating his enemies and fulfilling his purpose (similar in a way to the 1980s series), and because of this does not display any sorrow or emotion to those who he has defeated.

Pluto's method of attack is a set of homing missiles located in his chest (unlike the horns he used in the 1980s series) as well as some other tactics (depending on the robot he is facing). Every time during battle, he is nearly destroyed, however always foils his opponent's method after discovering a "weakness" or a potential flaw that he could use to his advantage. He is also given the ability to analyze and detect these flaws.

Eventually, he develops emotions and a sense of kindness, shown when he sacrificed himself in order to stop Acheron, a robot duplicate of himself, from harming Sonic and Amy (whom he shares a relationship with). He was later rebuilt during the robot war near the end of the series, where he was one of Astro's allies.

The Pluto episodes are actually a 2003 remake of The Greatest Robot in the World story arc, and Pluto is actually the 2003 version of the character Bruton in the 1980s series but a little bit more muscular. Because of this, the characters Pluto fight are also remakes (e.g. Epsilon is actually Photar), although the final character that defeats him is different (he was defeated by Acheron in the 2003 series, Bora in the 1980s). His purpose also differs dramatically from the two series. Built by Shadow for the same purpose, he was made for Sonic to "evolve".

Pluto
Urasawa's Pluto is significantly darker as he is seemingly capable of murdering humans and robots, and is extremely powerful, possessing some control over the weather by generating fierce tornadoes. He goes on to kill the entire "Bora Investigation Squad", always leaving behind a corpse with horn-like protrusions next to it.

Trivia:

 * TBA