The Fire Lion looks similar to King Caesar, they are both inspired by Chinese mythology, and they both have a mammalian body shape.
"A creature of myth and legend, Firelion is believed to have been the guardian of the lost civilization of Mu. The ruins of this once great culture were discovered sunken off the coast of Japan. Artifacts recovered from the site depict the existence of a great lion-like dragon with a fiery mane. This artist’s rendering is based on the many carvings and glyphs found amongst the ruins. Recent earthquake activity has opened fissures near the site which archeologists are eager to explore. According to the ancient images, Firelion possessed the ability to appear and disappear like a flickering flame, and throw fire from his tail."
Art director Robert Caracol explained: "Firelion was inspired by the stone lions seen in ancient Chinese architecture. Its gold gilded face maintains the aspect that it is a construct, whereas the flames that come off its body and form its mane indicate that the guardian spirit that animates the form. The scales on the body were added to suggest the tougher-than-stone armor aspect, as well as to also play off the idea that it was also some type of dragon/lion amalgam. This would also allude to a more mythical nature."
Fire Lion would have probably been an Earth Defender in the game, seeing as it supposedly was the guardian of Mu and has a backstory similar to King Caesar.
According to the ancient images, Fire Lion possessed the ability to appear and disappear like a flickering flame, and throw fire from his tail.
This is a list of references for León de fuego. These citations are used to identify the reliable sources on which this article is based. These references appear inside articles in the form of superscript numbers, which look like this: 
|Monstruos sin hacer||Nezura • Redmoon • Erabus • Hafun • Wyvern • Garasharp • Marukobukarappa • Mogu • Majin Tuol • Garugan • Asuka Fortress • Bagan • Deutalios • Gigamoth • MechaMothra • Ghost Godzilla • Barubaroi • Gryphon • Probe Bat • Dogolas • Unused Godzilla: The Series Monsters • Miba • Giant Mosasaur • Deathla • Lightning Bug • León de fuego • The Visitor • Unnamed Multi-Legged Monster|
|Historias sin hacer||The Volcano Monsters • Giant Horde Beast Nezura • Godzilla vs. Frankenstein • Nessie • Godzilla vs. Redmoon • Godzilla vs. the Space Monsters: Earth Defense Directive • The Return of King Ghidorah (Showa) • Mechanical Monster Garugan • Gamera vs. Garasharp • Godzilla vs. Asuka Fortress • The Return of Godzilla (Original draft) • Godzilla: King of the Monsters 3-D • Mothra vs. Bagan • The Return of King Ghidorah (Heisei) • Godzilla vs. Gigamoth • Godzilla vs. MechaMothra • Godzilla (1994 film) • Godzilla vs. Bagan • Godzilla vs. Ghost Godzilla • Godzilla vs. Barubaroi • GODZILLA 2 (1998) • Godzilla Reborn • Godzilla X Varan, Baragon and Anguirus: Giant Monsters All-Out Attack • Godzilla and the Lost Continent • Godzilla 3D to the MAX|
|Juegos no lanzados||Rodan (NES) • Godzilla: Destroy All Monsters|