In Incarnate Forme, Tornadus is based on Fūjin, the kami of wind. It may also have drawn some inspiration from Jinn. In Therian Forme, Tornadus is based on the Vermilion Bird.
An example of what is known as a “form change,” though I suspect this strange avian guise to be Tornadus's true form. Tornadus has been sighted crossing the ocean while in this form.
Due to being a pure Flying-type, Tornadus is the only Pokémon that can have the Flying-type backdrop in the Hall of Fame after defeating the Pokémon League in Pokémon Black and White and Pokémon Black 2 and White 2. This backdrop will always reflect the Pokémon's primary type, but all half-Flying-type Pokémon had Flying as their secondary type.
Tornadus is the only member of the Forces of Nature to be a single-type Pokémon.
In an interview with Nintendo Dream, Ken Sugimori revealed that Tornadus was originally intended to be colored red, to pair with Thundurus's blue. Tornadus's color was changed because the pair ended up looking too similar to Throh and Sawk.