Wrecker was a clone created on the planet Kamino. Like other soldiers in the Grand Army of the Republic, Wrecker was created from the genetic template of the bounty hunter Jango Fett with the intention of raising an army of identical warriors to defeat the enemies of the Galactic Republic. However, the cloning process contained a margin of error, resulting in the existence of beings that strayed from Fett's genetic code. One of these beings was Wrecker, who developed physical strength and stature far exceeding that of his fellow clones. Recognizing the strategic value in these genetic divergences, the Republic collected certain mutated clones to create an elite commando unit. This squad included Wrecker, as well as three other clones known as Hunter, Crosshair, and Tech. Together, they formed Clone Force 99, named in honor of Clone 99, who gave his life defending their homeworld during the Battle of Kamino.
Unofficially referred to as the "Bad Batch," Wrecker's squad went on several missions during the Clone Wars, a pan-galactic conflict between the Republic and the Confederacy of Independent Systems. During this time, the squad maintained a 100% success rate in their operations, traveling in an Omicron-class attack shuttle known as the Havoc Marauder. Although it was rare, the squad occasionally worked with regular clone troopers, though the Bad Batch often came at odds with the so-called "regs," with Wrecker claiming the squad's ship would always be shot down when traveling with such clones.
In 19 BBY, Wrecker and the other members of Clone Force 99 were sent to Yalbec Prime, where they were tasked with putting down an insurrection. During the mission, Wrecker cut off the stinger of a Yalbec queen while she was still alive, causing male members of the species to attack the team. Although squad leader Hunter believed that the Yalbec intended to eat them, Tech, the unit's information specialist, identified that Wrecker's actions caused the aliens to attempt to mate with the clones. Despite this, Clone Force 99 managed to escape the battle unscathed; while still on Yalbec Prime they received a message from Clone Commander CC-2224 "Cody," who requested the team's help on the planet Anaxes.
On Anaxes, Republic forces were caught in a tiring battle, struggling to defend the world from the Separatists. Led by Admiral Trench, the droid army seemed to be able to accurately counter the personal strategies of Clone Captain CT-7567 "Rex," leaving the clone forces baffled. With the consent of Jedi Generals Mace Windu and Anakin Skywalker, Cody planned to lead the Bad Batch behind enemy lines to a Cyber Center and learn more about the Separatists' plans. Touching down on the planet, the Bad Batch was joined by Rex, Cody, and fellow clones CT-5597 "Jesse" and CT-6116 "Kix" of the 501st Legion. Wrecker regaled the "regs" with stories of his victory on Yalbec Prime and boasted that he could single-handedly destroy the Cyber Center, despite Cody's insistence that the mission was solely focused on retrieval. En route to the Separatist base, the team's Low Altitude Assault Transport was shot down, a development which Wrecker found delightful.
Though most of the clones emerged unscathed from the crash, Cody had been caught underneath debris, trapping him in the burning gunship. Putting his trademark strength on display, Wrecker forced the transport to topple onto its side, rescuing the injured commander without assistance just before the LAAT exploded. Alerted to the Republic's presence, battle droids approached on the survivors' position. Hunter led the Bad Batch in "Plan 82," a battle strategy that saw Wrecker use the reinforced doors of the downed gunship as an improvised shield, protecting his squadmates as they engaged the enemy with Electro Magnetic Pulse grenades. Once most of the droids were destroyed, Wrecker rammed the doors into a DSD1 dwarf spider droid, blocking the output of its central laser cannon and causing it to detonate from within. In the aftermath of the skirmish, Wrecker brandished the disconnected head of a B1-series battle droid, pushing it into the face of the team's sniper Crosshair and mockingly suggesting that the droid liked him.
After regrouping at nightfall, Rex took command of the group and ordered the medic Kix to remain with an injured Cody until an evacuation team arrived. Wrecker and Crosshair took issue with the change in management, but Hunter assured the squabbling clones that they all fought for the same side. The next day, the unit came across an enemy security outpost. While the main squad ascended to the tower's upper level, Wrecker covered the structure's entrance and, to his dismay, did not participate in clearing the outpost's interior. But the brawler would have his chance to wreak havoc, as the group discovered that the Cyber Center was very close. Flanking the building on Flitknot Speeder Bikes, Force 99 stormed the base, allowing Rex and Tech to find that the center was receiving a live signal from Skako Minor. Rex discovered that the broadcast was being given by CT-1409, the clone designation of an Advanced Recon Commando named Echo who was thought to have been killed in action. With this intel, the group escaped and retreated back across Republic lines.
Determined to uncover the truth of his friend's disappearance, Rex convinced General Skywalker to lead a rescue mission to Skako Minor, with Clone Force 99 supplying transportation aboard the Havoc Marauder. En route to the planet, Wrecker continued to show off his abilities to Rex and Skywalker, lifting a PLNK-series power droid over his head with one hand while eating a deep-fried nuna leg with the other. Upon entering the planet's atmosphere, however, Wrecker placed the power droid down and threw the nuna leg aside, ready for action. Immediately on planetfall, the group were attacked by the native Poletecs; flying atop winged reptiles known as keeradaks, the aliens captured General Skywalker, bringing him into their village. Wrecker toppled a large boulder overlooking the village, giving the squad mobile cover as they entered the site, disarmed the Poletecs, and freed the general. After negotiating with the Poletec chief, the group was directed towards the Techno Union city Purkoll. Tensions rose once again between Rex and the Bad Batch; after the clone captain struck Crosshair for suggesting that Echo was better off left for dead, Wrecker restrained Rex and warned him against engaging with the squad. Skywalker broke up the clones, sending Force 99 to find an entrance into the tower base from which Echo's signal originated.
After discovering a turbolift that led into the structure, Wrecker became apprehensive of entering the facility, as he suffered from a fear of heights. Nevertheless, he ascended with his team, and took great joy in decimating the D1-series aerial battle droids that awaited them at the top. As more droids flooded the halls, Rex discovered that Wat Tambor, the leader of the Techno Union, had indeed captured Echo, transforming him into a cyborg and using his mind to predict the Republic's movements. Cornered in Tambor's lab and threatened by the organic-destroying Decimator, the team's only escape was a ventilation shaft in the ceiling; in order to reach the vent, Wrecker tossed each clone into the air, though General Skywalker, a Jedi Knight, was able to easily ascend to the opening. Before departing, Wrecker tossed multiple thermal detonators into the lab, ensuring that Tambor's experiments would not continue. Skywalker used the Force to lift Wrecker himself into the exhaust shaft, pulling the large clone into the vent just as the Decimator entered the lab.
Fleeing through the base's cooling systems, the team exited the facility through a door high in the atmosphere, intending to cross a thin pipe between towers to reach a landing pad. With no choice other than to confront his phobia, Wrecker crossed the gap with discomfort until the squad was once again cornered by droids. Wrecker was forced to dive off of the pipe in order to catch Crosshair, who had lost his balance in the chaos. Tech used recordings he had made earlier to replicate the cry of the keeradaks, summoning the flying reptiles and giving the squad a means of escape. The team was briefly followed by the winged D1 droids, but the Bad Batch swiftly shot down the droids and returned to the Poletec village. Tambor would not so easily let his "property" escape, however, and sent further reinforcements after the Republic unit. During the defense of the village, Wrecker again used his power to throw Rex and Hunter into the air, this time to take out the photoreceptors of octuptarra tri-droids. One such droid nearly crushed some of the villagers beneath its legs, but Wrecker pushed the Poletecs aside, grabbing the tri-droid's limb and holding it in place until General Skywalker toppled the walker with the Force. With Echo rescued and the village safe, the team returned to Anaxes.
During the closing phase of the battle, Wrecker, his squad, Rex, Skywalker, and Echo boarded Admiral Trench's flagship, allowing Echo to transmit a signal that shut down the Separatist army below. After escaping the Providence-class Dreadnought, Skywalker gave Wrecker a detonator he had stolen from the bridge. Overjoyed at the chance, Wrecker was allowed to annihilate the entire Confederate fleet over the planet, securing a Republic victory. The squad later decided to leave before the medal ceremony, but Sergeant Hunter, realizing that Echo was no longer a regular clone, offered the corporal a place in their squad. Echo agreed to join the commandos, parting ways with Rex when he and the rest of the Bad Batch saluted the Clone Captain.