The Krudzu Hybrid Hydra was an advanced robot experiment created by Dr. Ivo Robotnik, prior to his final battle with Sonic the Hedgehog in Operation: EndGame. An evolution of the original Krudzu, it possessed the ability to absorb machinery-particularly robots-and incorporate them into its form, as well as becoming incredibly durable. Following the destruction of Robotropolis, it managed to survive, and would go on to battle Sonic on a number of occasions: first independently, and later as an agent of Robotnik's alternate counterpart, Dr. Eggman.
One Tough Weed
According to Snively, the Krudzu Hybrid Hydra was originally created by Dr. Ivo Robotnik to combine "many older Badniks and killer robot ideas into one monstrous creature". It was only in the testing stages when Station Square launched a nuclear assault on Robotropolis, and Snively had believed it to be destroyed, but a lone root of the experimental Badnik remained untouched. Buried deep underground until the destruction had settled, it ascended to the surface and scavenged the damaged and destroyed robots around it, incorporating them into itself. "Like the Hydra of legend," as it would later explain, it "re-grew into [this] fearsome creature." (StH: #110, FCS: #4)
After the fall of the Iron Dominion, Sonic the Hedgehog made a trip to New Megaopolis to search for the missing Dr. Eggman. Though he arrived at a dead end in the EggDome and found no trace of his adversary, he was surprised by the Krudzu Hybrid Hydra that caught him instead. The plant explained the means of its reappearance and attacked Sonic. Sonic was amused (and somewhat disturbed) by the reappearance of the badniks of his childhood and tore the plant to shreds-but it quickly regrew at full strength and engaged Sonic again. Just as the monstrosity was about to finish Sonic off, a mysterious weapon in the form of a robotic hummingbird struck the Krudzu Hybrid Hydra, short-circuiting it through unknown means and causing an electrical explosion that left Sonic confused. Tired, Sonic left behind the charred remains at the Eggdome, returning home. Unbeknownst to any of them, the weapon was created by Dr. Eggman who refused to allow the machine to defeat Sonic as it was not one of his own plans, but instead the plan of the Dr. Robotnik that he replaced. When asked why he saved Sonic, Dr. Eggman explained himself to the confused Snively, saying, "I have dibs on Sonic, Snively. No one will rob me of that. Not even myself." (FCS: #4)
Weeks later, a single surviving sprout of the Hydra was discovered by Eggman aboard his Death Egg Mark 2. In order to delay Team Fighters while he attacked Albion, Eggman gave the Krudzu a second chance at destroying Sonic by allowing it to merge with an incomplete Titan Metal Sonic. Despite its intimidating new form, Team Fighters defeated the plant-possessed mechanical monstrosity, knocking it into the ocean on the Mercian coastline. Before it disappeared beneath the water, the Krudzu vowed it would have revenge. (StH: #241).
True to its words, the Krudzu Hybrid Hydra survived the Titan Metal Sonic's destruction, taking control of a Crabmeat in order to protect itself from the water and from the rain that began falling when it emerged on Albion. It went on to possess the body of Metal Knuckles, who had been knocked out during the battle in Albion, by repairing the robot before setting out to get revenge on Sonic. While Team Fighters and Knuckles the Echidna were busy fighting Thrash the Devil and his pack of Devil Dogs, the Krudzu Hybrid Hydra in the body of Metal Knuckles launched its attack by ambushing Tails and Amy Rose and grabbing them with its long vines. After a brief struggle, Sonic managed to rip the vines holding Tails and Amy and overpowered the robot. After Sonic claimed that he smashed everything the creature used and that there were no Badniks for it to use either, the Krudzu Hybrid Hydra corrected him saying that it did not need Badniks and that all it needed was machinery and added that anything could make it stronger. It then managed to seemingly fuse with the various machinery that was laying around, resulting in a new monstrous form; however, it was stunned by Shard the Metal Sonic, who was initially watching the fight in secret. (StH: StH #244, #245).
Recovering from the blow, the Hydra seized Sonic and Shard, only for them to start dragging it around Albion with their super speed. This culminated in the pair sending it flying towards Amy, who sent it flying through several buildings with her Pico Pico Hammer. Defiant, the Hydra claimed that the four of them couldn't defeat it, only to be set upon by their unexpected new allies: the Devil Dogs. Between the Mobini and the heroes, the Hydra was torn to shreds, leaving only a small sprig still active, which Sonic then picked up. It was then turned over to Shard, who suggested that it could be used as means of Mecha Sally's De-Roboticization. Contained in a small jar, the Hydra was then taken with Shard back to New Mobotropolis, with Sonic thinking that it might also eventually prove useful in rescuing the banished Echidnas. (StH: #246)
Having been created by Dr. Robotnik to destroy Sonic, the Krudzu Hybrid Hydra is obsessed with eliminating the Hedgehog. It was actually thrilled to meet Sonic for the first time, having feared that the destruction of Robotropolis meant the end of its chances to destroy him. Despite this, the Hydra is cold and sadistic, and delights in causing Sonic and his allies pain. It is also single-mindedly loyal to Dr. Eggman, in spite of-or perhaps in ignorance of-the doctor's previous attempt to completely destroy it.
The Krudzu Hybrid Hydra's most notable ability, which sets it apart from the original Krudzu, is it's ability to incorporate machinery into its form. Its first incarnation consisted primarily of the remains of various Badniks, while in subsequent incarnations it would resemble a single robot with Krudzu growing from it. Due to adapting a Crabmeat Badnik, it overcame its original vulnerability to water. The Hydra is also capable of surviving immense damage, and even the smallest remnant is enough for it to regenerate and continue posing a threat. Like its former incarnation, the Krudzu Hybrid Hydra has the ability to speak through whatever technology it happens to be possessing at the time.
The Krudzu Hybrid Hydra initially appeared in a form much like its name would suggest: a large, multi-headed dragon-like being with a green plantlike body and various robot parts and machinery incorporated into its form. In addition to its visible Badnik heads, the Krudzu Hybrid Hydra possessed Crabmeat's pincers, Ballhog's bombs, SWATbot blasters, Caterkiller's spiky body (wielded as a flail), Burrobot's arms and drills, spiked balls probably used by Orbinaut, and unidentifiable claws and blades possibly taken from factory equipment or built on its own.
In its second appearance, the Hydra briefly appeared as a small root before taking command of a Titan Metal Sonic unit, leaving the large robot with Krudzu in evidence on its form. Similar appearances came about as the Hydra incorporated first a Crabmeat and then Metal Knuckles. After absorbing various machinery lying around the ruins of Albion, it took on a monstrous form, its most recognizable elements being Metal Knuckles' head and torso and giant versions of Crabmeat's claws.