Dragons are generally presented as non-anthropomorphic reptilian creatures. They also generally possess a pair of wings (as the Earth Dragon lacks them). Dragons also have horns on their heads in varying locations, with said horns varying in size and design. Dragons on earth are quite diminutive, while those in the world of Camelot are giant behemoths.
Characteristics and culture
Dragons in the world of Camelot generally appear to live in isolation, as they are not often seen with others of their kind. They also seem to prefer to live in caverns, as both the Earth Dragon and numerous thunder dragons have also been seen living in such environments. The dragons on earth act quite different, behaving almost like household pets.
Powers and abilities
Dragons often possess special abilities, such as being able to breath fire and create lightning, and are also capable of flight thanks to their wings. Those in the world of Camelot are also very resilient creatures, being able to take multiple battle wounds from the Knights of the Round Table and Sonic himself without much visible damage.
In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, Dragons retain most of their real-life features, despite being anthropomorphized, though not to the extent of other Mobians, evidenced by their general anatomy (lack of bipedal and humanoid features). In this media, they too are a by-product of the Gene Bombs used on the world by the Xorda. While they lived alongside other Mobians in recent history, they soon went into hiding upon Robotnik's takeover of the majority of the world, wherein he roboticized a massive number of dragons, forcing the remaining ones to go into hiding. However, after Dulcy saved the hiding dragons from Eggman, communications with the outside world were eventually reestablished.
In the post-Super Genesis Wave timeline, Dragons appear to more akin to the rest of the anthropomorphic creatures than before, as members like Dulcy have a far more similar and humanoid appearance, and even wear clothes, unlike before. They are still capable of flight via their wings and posses special breaths, such as breathing fire and ice.
Sonic the Hedgehog (TV series)
In the Sonic the Hedgehog television series, dragons have a near identical anatomy, history of robotization and decline, and powers to the Dragons of the Archie Comics. In the present, only a few dragons remain, including Dulcy.
In Sonic the Comic, Dragons are a species that are mentioned, with only one of its members being seen. They hibernate for multiple milleniums at a time underground, and thus, also live extremely long lives. Like most incarnations, they are able to breath fire and can use their wings to fly.
In addition to the seven pre-existing species, the Avatar in Sonic Forces was meant to have Dragon as a possible species. However, that idea was later cancelled.