Jet Jaguar is a robot built by Yumi Nagata's grandfather before he was killed by Godzilla during his rampage in 2004. He was first activated in 2010 and has repeatedly helped Godzilla multiple times before going into shutdown mode following The Trilopod War.
In terms of design, Jet Jaguar's body resembles a human or humanoid in appearance and body structure. His body is silver but different parts of his body are painted red, yellow and blue. The lower part of his legs are blue while is knees are yellow, the outer-sides of his legs are red and the rest are silver. His groin is yellow and his waist is both red and yellow, on his waist is a Y-shaped symbol. The lower part of his chest is silver while the upper part is red, the same applies to his back. His shoulders are yellow, his elbows are blue and the rest of both arms are silver. His neck is blue and his head is silver. His head is shaped almost like a cone with some almost ear like protrusions. His eyes are completely black and he has a permanent smile on his face.
Jet Jaguar has been shown to have gained sentience throughout his appearances and behaves very much like a superhero, fighting and putting himself in harms way to protect others. When he isn't fighting, he is shown to be incredibly kind towards others and was shown to be quite placid when he attempted to calm Godzilla down when he went on a rampage after defeating Gigan in Las Vegas.
Each time Jet Jaguar has made an appearance, it was during events involving Godzilla, leading to a possibility that he possesses some type of connection with him.
According to Dr. Yumi Nagata, Jet Jaguar was created by her adopted grandfather, who made her promise to keep his existence a secret before his death during Godzilla's rampage in 2004. Dr. Nagata has been in possession of the robot since then, living up to her promise to her grandfather to keep Jet Jaguar's existence a secret as the robot remained dormant during the following Kaiju attacks. But when the Cryog's arrived and attacked Las Vegas, Jet Jaguar awoke from his dormant state.
During the attack on Las Vegas by Gigan and Orga, Jet Jaguar awakened from his dormant state and arrived in the city to aid Godzilla, flying into Orga's mouth and growing into his Giant Form to blow him up from the inside. When Jet Jaguar tries to show Godzilla that he means him no harm, Gigan recovers from being attacked by Godzilla and the two realize that they have a common enemy. Teaming up, the two are able to overwhelm Gigan until Jet Jaguar notices Orga's body slowly regenerating and he begins to repeatedly stomp on his body to prevent him from fully healing. Jet Jaguar is then attacked by an escape pod sent by the Cryogs that retrieves the remains of Orga's body before it escapes. Jet Jaguar then notices Godzilla begin to go on a rampage after driving Gigan away and tries to calm him down, only to be blasted by his Atomic Breath and is forced to fight back, knocking Godzilla out with one punch to the face before carrying his unconscious body out to to sea. His sensors then detect something and he flies away. He then attacks the Cryog ship where C.K.R. soldiers Woods and Chavez are and saves them by freezing a majority of the Cryog soldiers with the Ice Box, a freezing weapon created by the C.K.R. soldiers. After saving them and bringing to an aircraft carrier, he senses Orga's pod retreating from the planet and begins to go into shutdown again.
Later while Godzilla is fighting Titanosaurus, Gezora and Manda, Jet Jaguar protects the crew of an aircraft carrier from Destoroyah. Although he is able to fight on par with her, he is wounded when Destoroyah strikes him with her Oxygen Destroyer Ray, but manages to supposedly kill her by freezing her with Kiryu's Absolute Zero Cannon then smashing her into pieces. When Jet Jaguar learns that Godzilla is beneath the sea fighting the other Sea Monsters, Jet Jaguar races to save him from being blown up by submarine missiles, but is too late as Godzilla is supposedly killed after being buried beneath the ocean floor as the Devonian city is destroyed. Jet Jaguar later goes missing beneath the Pacific when he tries to find Godzilla.
Trilopod War Arc
During the battle between the Terran Kaiju and the Trilopods in Los Angeles, Jet Jaguar returns and saves a small group of C.K.R. from a Trilopod Godzilla, but is injured when the hybrid strikes him with its Atomic Breath. He is then saved when Zilla arrives in the city and attacks the Trilopod Godzilla, then notices the Cryog Command Ship hovering over the city and flies towards. When he arrives, he is confronted by a fully upgraded Gigan and the two begin to battle, during which Jet Jaguar manages to pierce the ship with one of Gigan's chainsaws just as the ship blows up after striking Magita. After Godzilla manages to destroy Magita, Jet Jaguar along with the other kaiju witness Godzilla heading out to sea. In the aftermath of the battle, Jet Jaguar is seen in shutdown mode and being repaired by Dr. Nagata and Dr. Kenji Ando.
Post-Trilopod War Arc
While Jet Jaguar himself doesn't appear, he appears in Godzilla's memories as the Shobijin show the core members of Fairy Tail after the Earth Defenders were transported to Earth Land. As the Fairy Tail mages witness Godzilla's memories, they see Jet Jaguar in his battles with the Trilopods and Gigan.
Immense Strength: Jet Jaguar possesses super-human strength to the point that he was able to knock Godzilla unconscious with just a single punch and even carry him with ease while in flight. He was also shown to be strong to fight on par with other physically strong Kaiju such as Destoroyah, Gigan and Orga.
Immense Durability: Jet Jaguar has been shown to be very durable, being able to survive attacks that would destroy most other Mechas. He is capable of surviving a point-blank blast from Godzilla's Atomic Breath, Destoroyah's Oxygen Destroyer Rays, and being slashed by Gigan's upgraded chainsaw arms.
Enhanced Speed: Jet Jaguar is able to fly at great speeds, supposedly at Mach 3.5. He has even been shown to fly at these great speeds while carrying extremely heavy objects and even other Kaiju like Godzilla. He is also quite agile to the point that he can fight toe-to-toe with other quick-moving Kaiju such as Gigan.
Intelligence: Jet Jaguar's intelligence is greatly emphasized, being smart enough to learn how to pilot Kiryu without any sort of training. He has also been shown to posses sentience and self-awareness like normal humans.
Size Manipulation: Jet Jaguar is capable of shrinking himself to the size of a human and growing to the size of a skyscraper when he is fighting other Kaiju. He has also been shown to use this size changing ability as an advantage against his enemies in combat when he flew into Orga's mouth in human size before growing into his Giant Form to blow him into pieces from the inside.