Shapeshifting is the ability to alter one's shape in a variety of ways, either to grow claws, fangs, change the color of their eyes or increase height and overall physical size. Both supernatural and un-natural creatures have been known to possess this power.
Species that can shapeshift
Most of the Chimeras were granted the shapeshifting power possessed by their true supernatural counterparts by the Dread Doctors, with Corey Bryant being the only known Chimera who did not acquire this power. Theo Raeken and Hayden Romero, a Werewolf/Werecoyote hybrid and a Werewolf/Werejaguar hybrid respectively, could shapeshift their features into those of a true Beta Werewolf, including golden eyes, fangs and claws, but Theo could also transform into a real wolf due to his Werecoyote side and Hayden could transform her skin to resemble that of an actual Werejaguar while Tracy Stewart, a Werewolf/Kanima hybrid, also had the same glowing golden irises, fangs and claws of an actual Werewolf as well but her eyes eventually changed to resemble the eyes of a Kanima and her Kanima half also gave her the scales and the tail of a Kanima and the ability to create a paralytic venom from her claws but her tail was eventually cut off by the sword of Kira Yukimura and did not seem to grow back. Meanwhile, Josh Diaz, a Chimera whose two species that make up his pseudo-supernatural nature remain unknown, possessed unique features: glowing purple eyes, glowing purple claws and fangs that were never seen in another supernatural creature.
The only two Hellhounds to have appeared in the series, Jordan Parrish and Halwyn, can alter their body by having glowing orange eyes, black charred claws, large fangs and a magma looking body that gives off heat. They can completely engulf their bodies in fire at will.
Jackson Whittemore, the only full-blooded Kanima to have appeared in the series thus far, rejected his transformation after being bitten by Derek Hale in Season 1's Code Breaker and became the Kanima due to his unresolved identity issues due to him being an orphan and adopted child. His transformation into a Kanima not only gave him superhuman physical attributes that were superior to the majority of Werewolves, even Alphas such as Derek, but also gave him the power to transform into a lizard/snake-like creature with patterned black scales, slit reptilian eyes, double rows of sharp teeth, huge talons and a tail. His talons and tail produced a venom that could paralyze any living being in seconds.
Even after Jackson was saved by his ex-girlfriend Lydia Martin and turned into the Werewolf he was meant to be, he still retained some of his Kanima abilities: his claws still produced Kanima venom, he could show his reptilian eyes (along with his normally blue Werewolf eyes) and he could extend and retract his tail, which he used for numerous feats. However, these features required a significant amount of effort to be triggered and Jackson himself admitted he could no longer fully-shift into a Kanima.
Kira Yukimura and her mother Noshiko Yukimura, as Thunder and Celestial Kitsunes, respectively, can make their eyes glow orange while the Nogitsune, also known as Void, can have large metallic fangs and glowing white eyes.
Löwenmenschen, as wolf-lion hybrids, possess the power to shapeshift their features into that of the aforementioned species, including glowing eyes, fangs, claws, mutton chops, pointed ears, and ridged brows. The only known Löwenmensch, the Alpha Garrett Douglas, had glowing red eyes, so it can be assumed that they can also have gold or blue eyes like Beta or Omega-level Werewolves.
Wendigos can shapeshift to gain white glowing eyes and large shark-like multiple rows of teeth.
Werewolves have the ability to shape their features into that of a partially lupine form, which involves glowing eyes (which can be red, blue or yellow) fangs, claws, a ridged brow, pointed ears and large sideburns. They can change involuntarily when overcome by the influence of the full moon or by intense emotions, such as anger or stress. With the proper training, Werewolves can avoid shifting in front of human civilians and learn how to only transform a few selective features as needed, such as only extending their claws to cut something, their fangs to bite something, or simply making their eyes glow to enhance their eyesight or display their supernatural nature.
Werecoyotes are capable of having the same shifting capabilities of their wolf cousins, gaining the typical ridged brow, furry sideburns, pointed ears, fangs, claws and glowing eyes (either golden yellow or cold blue). Just like Werewolves, Werecoyotes are vulnerable to the full moon and emotions that increase their heart-rate, putting them at risk of losing control over their transformations and exposing themselves to innocent humans but they can remain human in most of the situations if trained properly. Some Werecoyotes seem to be capable of advanced shapeshifting though it is unknown if Malia is a unique case.
Werejaguars are capable of transforming their features into those of a jaguar. They acquire blue skin with black spots, glowing jade green eyes and sharp fangs and claws. Like their Werewolf and Werecoyote cousins, Werejaguars can involuntarily shift and attack innocent humans due to the full moon or emotions, such as anger or fear, which is why they must be trained to avoid exposing themselves as supernatural creatures to humans and Hunters alike.
Some supernaturals such as werewolves, typically Alphas (though occasionally Betas and Omegas as well), can shapeshift into more animalistic forms, such as transforming into a full wolf, or into a more beast-like monstrous form. Most Alphas don't use their beast form however as for some reason they prefer to shift like Betas, it is possible that there may be a stigma against it as the twins Ethan and Aiden considered what Peter became to be bad.
Peter Hale during his stint as an Alpha, Peter would frequently transform into a huge monstrous beast that would usually be the typical form of Werewolves in modern fiction. In this form, Peter was nigh unstoppable and had to be hit with a molotov cocktail twice just to neutralise him.
Jackson Whittemore as a Kanima would fully transform into a lizard-like beast complete with a tail. In this form, he was more than a match for an alpha and two betas and it was revealed that this is not even a Kanima's final form as they can transform even further, developing wings according to the bestiary.
Scott McCall almost transformed into a beast form during his fight with the deadpool assassins as his face began morphing even more than usual and becoming similar to Peter's.
The Beast of Gevaudan has displayed the most advanced form of shapeshifting to date as Sebastien could summon shadows to transform himself into an eight or nine foot tall monster that was so powerful that it took most of Scott's pack and his Hunter and Hellhound allies to defeat the Beast. The Beast resembled little of an actual werewolf, being a true monster than anything animal, with large red veins spread throughout his body and bone spikes on his elbows and knuckles.
Full animal form
Talia Hale was well known in the supernatural community for being able to become a true wolf, something that was rare amongst Alphas, however, her Omega son Derek Hale demonstrated this power after evolving and being the first Omega werewolf to possess this level of shapeshifting.
Laura Hale was also seen in a true wolf form suggesting that such a power may be genetic.
Malia Tate is able to transform completely into a coyote, it is unknown if this is unique to Malia or its something that all Werecoyotes can do, Theo Raeken, a Chimera Werewolf/Werecoyote hybrid is also able to shift into a true wolf but its unknown if its due to his Werecoyote side or a side effect of his unnatural existence. Malia Tate is also a Hale, meaning her ability to fully shift could partially be due to heritage.