Biolizard

"Could this be the prototype of the ultimate life form that was supposed to be encapsulated?!"

- Knuckles about the Biolizard.

The Biolizard (also known as "The Prototype of The Ultimate Life Form") is a giant bio-mechanical creature and the final boss of Sonic Adventure 2. It appears as a giant lizard with a life support system on its back with tubes running down its neck to its head. The Biolizard is 85 meters (280 feet) long, 30 meters (100 feet) wide, 19.5 meters (64 feet) tall, and weighs 87.5 tons. After the final version of the Ultimate Life Form was created, the Biolizard was to be encapsulated but never was.

Personality
The Biolizard was akin to that of a primal animal. It was unruly, reckless, and hostile to the point that even the researchers feared for their lives. The Biolizard was sensitive to humidity changes and air temperature, and reacted violently to the power of the Chaos Energy given off by the emeralds.

Background
The Biolizard was an early version of "Project Shadow", a government project run by Doctor Eggman's late grandfather Professor Gerald Robotnik that was intended to create an "Ultimate Life Form" as a first step towards humanity discovering the secret of immortality. This creature is an ultimate immortal, or so the scientists thought. Due to the experiments weakening the Biolizard, it later needed a life support system. While the Biolizard was successful in the way that it could regenerate, restore itself, and self-reproduce, it was also unruly and dangerous. It was closed down when Gerald, with the aid of the alien Black Doom, produced a more advanced being: Shadow the Hedgehog.

When G.U.N. came to Space Colony ARK in order to put a stop to Gerald Robotnik's plans, they found the Biolizard and shut it down. It didn't go without a fight, however, and it destroyed almost the entire group of GUN soldiers. Somehow Gerald Robotnik retrieved and programmed the creature to destroy the Earth, by fusing with the ARK to keep it on its collision course as a contingency plan in case someone tried to interfere with his original plan.

Sonic Adventure 2
The Biolizard remained in suspended animation aboard the ARK until the present day, when Doctor Eggman placed the seven Chaos Emeralds into the Eclipse Cannon. This initiated a program created by Gerald Robotnik, which used the power of the Chaos Emeralds to send the ARK into a collision course with the Earth. Eggman joined forces with Sonic and friends to prevent this doomsday scenario, and they tried to pull the ARK into orbit again by using Knuckles' Master Emerald to deactivate the Chaos Emeralds.

However, when Sonic and Knuckles entered the cannon's core, the Biolizard awakened, determined to keep the ARK on its path to Earth. Later, Amy Rose convinced Shadow to help save the Earth (Shadow had a flashback about his best friend, Maria Robotnik) and Shadow fought and won against the giant reptile by damaging its life support system. The Biolizard then used Chaos Control to teleport outside and fuse with the space colony itself, becoming the Finalhazard, the final boss of the game. It was fought by the combined power of Super Sonic and Super Shadow, who then used Chaos Control to place the ARK back into orbit. Both Shadow and the Finalhazard fall to their apparent deaths (though it is later revealed that Shadow survived).

Shadow the Hedgehog
The Biolizard was not mentioned in Shadow the Hedgehog, except in one of Shadow's flashbacks, where he remembers his apparent death after defeating it. The Biolizard was likely just an example of Gerald's work before Black Doom assisted him, and thus is of little interest to the Black Arms and was never stable because he never had Black Doom's DNA. However it is noted that after Black Doom transforms into Devil Doom, he has an identical cry to that of the Biolizard. Several other Black Arms have similar cries. Also the Black Annelide, Black Worms, and Death Leeches have a skin texture very similar to the Biolizard's. This presents the possibility of the Biolizard actually being a Black Arms experiment, but it was simply unsuccessful (or not successful enough). As it turns out, Devil Doom and the Biolizard's cry is just a reused version of Perfect Chaos' cry, and the Biolizard is just a lizard that was horribly mutated. The fact that it has the same skin color as the Black Arms is probably because Sega reused the skin color for the Black Arms, and therefore might be a coincidence.

Sonic Generations
The Biolizard appears in Sonic Generations (3DS) as a boss of the Dreamcast Era. The battle is almost similar to how Shadow fought it. After beating it, Sonic says that he has fought it before, which is ironic as he only fights it as the FinalHazard in his Super State with Super Shadow. It's unknown if the Biolizard was revived or a copy made by the Time Eater.

Boss Battle
The Biolizard fights by spitting dark energy balls, biting, or lashing its tail at Shadow. After chasing the hedgehog for some time, the lizard stops and seems to hyperventilate, which is Shadow's chance to grind up a green tube that connects the Biolizard's head to its life support system and attack it. After damaging the system a few times, the Biolizard creates dozens of pink egg-like orbs in the air, and fires them at Shadow. Shadow must then use homing attack on the orbs in order to get into the air and attack the life support system again. Finally, the Biolizard will somehow lift Shadow himself up into the air along with the orbs, and as such he must float towards the life support system while avoiding the orbs in order to defeat the Biolizard.

Boss Battle (Phase 2)
After transforming into the Finalhazard, the Biolizard also gains the ability to fire large pink energy beams from its broken life support system, and create similar orbs to the one before. Only the new ones are red and the Finalhazard creates hundreds of them to cover itself as a shield. It also fires them at Super Sonic and Super Shadow a few at a time. As his life support system has been demolished, the Finalhazard has grown large pink boils all over its body, and Super Sonic and Super Shadow must charge into these boils in order to harm the boil on its body.

Sonic X
The Biolizard's role in the anime Sonic X parallels the one it plays in Sonic Adventure 2. It appears in episode 38. But the creature is not specifically named as a prototype of Project Shadow. In the original Japanese version, Knuckles identified the Biolizard, but in the English dub, it was unnamed, and Knuckles instead simply stated that he would never let the monster get the Master Emerald. When Professor Gerald's diary reveals what really happened on the ARK 50 years ago, a small green lizard was shown that could have been what the Biolizard looked like before its current state.

Archie Comics
The Biolizard appears in the Archie Comics Sonic the Hedgehog and it spin off comic-book series following the Sonic Adventure 2 comic adaption. However it was not until Sonic Universe #2, which retold the story, that the Biolizard made a physical appearance.

Like in the games, the Biolizard was created by Professor Gerald, but was later used by Gerald as a part of his plans to destroy Mobius to avenge Maria's death. When Sonic and Shadow tried to foils Gerlad's plan, the Biolizard attempted to make the Space Colony Ark collide with the planet, but was defeated by Super Sonic and Super Shadow.

Trivia

 * Since its first appearance, the Biolizard has become one of the most popular and liked bosses of the Sonic games.
 * As the Biolizard is the prototype of Shadow the Hedgehog, it could be considered the "brother" of Shadow the Hedgehog.Project_Shadow_File.jpg
 * According to Rouge's report in a cutscene in Sonic Adventure 2, Biolizard was made on January 27 at 12:30 a.m. The report also claimed that its eternal engine and organ for activating Chaos Control were working nominally, although it yielded higher results than expected. The Biolizard was also noted by Professor Gerald Robotnik to have grown to 2.7 meters and 350 kg only a couple of days after its "birth," thus resulting in his request for the control of its vital organs to be reinforced. During the time of the report, it was also noted to not be able to walk yet, although its neck and tail were already powerful, possessed sensitivity to temperature changes, and then-currently had a low learning rate, making it closer to an animal, and thus requiring that the Biolizard be under observation.
 * According to Rouge's report in the official strategy guide from Sega, the pink-orb objects the Biolizard produces are produced through asexual reproduction, which means that there could have been more than one Biolizard, however this is unlikely. It is often assumed that the Biolizard, is in fact, female (due to the eggs), but this is unlikely because, additionally, the Omochao that appears during the battle refers to the Biolizard as a "he". The misconception is due to the fact that it appears to reproduce asexually, however asexual reproduction is largely done by species without clear gender differences and in the case of the Biolizard it is most likely that it's hermaphroditic.
 * When Biolizard summons the pink spheres and later levitates Shadow, the roar used is the same roar used for Perfect Chaos in Sonic Adventure, but with a different pitch. In the 3DS version of Sonic Generations, Biolizard 's roar is now reused from Dark Gaia Phoenix from Sonic Unleashed.
 * The Dreamcast version of Sonic Adventure 2 had glitches in the game that led to unavoidable deaths when fighting the Biolizard (such as landing in the water as opposed to on the platform).
 * When playing the Dragon Slayer mission in Sonic and the Black Knight, Sonic sometimes mentions the Biolizard. The Earth Dragon, in fact, may be the Arthurian version of the Biolizard due to being so similar in body type, having the same neck, and even a similar roar.
 * When the Biolizard becomes Finalhazard, it loses some limbs like a missing arm, which might have been caused from its fight with Shadow or when attaching itself to the Eclipse Cannon.
 * The_Ugly_Prototype.jpg Sonic X and Archie comics, the Biolizard appears to have back legs, while in Sonic Adventure 2, it has 2 flipper like appendages located in front of its tail.
 * After defeating the Biolizard in Sonic Generations (3DS), the following cutscene shows Sonic saying he fought it before. Technically, he did not fight the Biolizard in its normal form (it was fought by Shadow) but he did fight it when it transformed into the Finalhazard.
 * In the boss theme "Supporting me ...for Biolizard", a remixed part of "Live and Learn", was put into the song.
 * It could be said that the Biolizard wasn't willingly evil, but was merely reprogrammed by Gerald Robotnik. Although its said to be a primal violent creature prior to being abandoned and eventually encapsulated.