In the Beast Wars continuity, when the Maximals and Predacons crash land on Earth, their robotic forms are subjected to the Energon-rich environment and have to take on animal forms to shield them when they step outside. Though it helped them survive, they suffered when it came to combat and had to eventually retreat before exposure destroyed them. However, as their transforming capabilities evolved, certain characters underwent more aggressive evolutions. One example is Cheetor, whose final evolution turned him into the Transformers equivalent of a werewolf.
Following the series' second season, the Maximals and Predacons underwent another evolution into a Transmetal form. This form acts as a way to bolster the mechanical aspects of the robots and give them offensive capabilities while in animal form. For example, Rattrap became a car in his beast form, while Cheetor and Optimus Primal could fly via jets or a hoverboard. They could undergo this mutation thanks to an energy wave known as the Quantum Surge that covered the Earth.
As the Maximals get more accustomed to their new bodies, they learn of an object known as the Transmetal driver that has been used in cloning experiments. Cheetor manages to get the driver away from Megatron, but seemingly at the cost of his own life. Megatron shoots him into an electrical arc that overloads his systems, but he returns to his team badly damaged. Then in Season 3, Episodes 5-6, "Feral Scream," he turns into a mutated version of himself that attacks the Maximals and Predacons; however, it does repair Cheetor once he reawakens from his "nightmare."
In reality, Cheetor's body is going through a secondary metamorphosis known as Transmetal 2 that further blends his body's mechanical and organic aspects. In the resulting transformation, Cheetor struggles with his control over his body and consciousness. He also tries to hide it from Optimus to keep them from worrying but ends up having to use it to fight another Transmetal Predacon named Dinobot 2. Eventually, the Maximals are able to assist Cheetor, though it isn't easy. He nearly loses himself to his beast form before coming to his senses. However, his appearance isn't the only thing that changes.
Once fully changed, Cheetor is much more mature than he was in the past, and also moodier. To compare, he acts much more like a teenager rather than a child. This helps in combat, as he's much more confident in battle and able to hold his own. However, his typical excitement makes way for cockiness that irritates his teammates. Rather than tell the story through a traditional narrative, the episode instead decides to take the approach of a monster movie.
Cheetor is one of the few transformers to undergo the Transmetal 2 change, but he wears it well. While his new chapter started as something akin to Lon Chaney Jr.'s The Wolf Man, he quickly turned the negative into a positive and became a powerful teammate. This would be the last form he would take in the Beast Wars cartoon, but while it put the Maximals in a horror movie, it also represents Cheetor's growing maturity.