We were told that there would be flightless dragons on the show, and it looks like we've found one of them! Cartoon Network uploaded images of the Fireworm as part of a "dragon manual" they have started to build on their website.
Along with Fireworm, we found the name "Smothering Smokebreath," presumably another dragon. Unfortunately, there are no images for the Smokebreath yet.
Check below for stats and images of the Fireworm!
UPDATE 9/25: Check below for a new picture and stats of the Smothering Smokebreath from Wild Skies! Thanks Serimon and barracuda!
UPDATE 9/27: New info image for the Fireworm.