Hobblegrunt

The Hobblegrunt is a new Stoker Class dragon that made its debut in the movie, How to Train Your Dragon 2.

Dragon Appearance
The Hobblegrunt has a single nasal horn and and an expandable frill surrounding its head. It has clawed wings, small arms and big legs like a Deadly Nadder. It also appears to have long neck and tail as well. Its tail has frilled edges, similar to that of a Monstrous Nightmare. The Hobblegrunt doesn't have a particular colour, but instead it changes colour depending on its mood:
 * Yellow: Happy
 * Purple: Curious
 * Red: Angry

Notable Abilities

 * The Hobblegrunt is able to change its colours like a chameleon and even for similar reasons, contrary to pup ulnar belief chameleons change color to communicate and show their emotions, similarly to the Hobblegrunt, and this ability is similar to that of the Changewing. Instead of doing it for defensive purposes, it changes color depending on its mood. It can use this ability to calm other dragons.
 * Using the large frill on its head, the Hobblegrunt is able to detect the subtle shifts in temperature, barometric pressure, and the emotional states of nearby dragons or humans.

Titan Wing
Source: Dragons: Rise of Berk

Titan winged Hobblegrunts have a large frill with small 'horns' on its edges. It has two large pale pink spots on it. They are mainly light blue in colour. Their neck is clearly segmented and their winks have pink rings on it. Additionally, these Titans have grown four small spikes on their long, slender tail and a sail-like fin on its back.

Known Hobblegrunt

 * Gruff
 * Primal Hobblegrunt

Trivia

 * Valka owns an adolescent Hobblegrunt named Gruff that was blinded by a tree snare trap.
 * The Hobblegrunt is the second dragon species that is able to change its colours, with the first being the Changewing.
 * Although the 'Guide to the Dragons' stated that the Hobblegrunt was a Boulder Class dragon, the official website later revealed it was a Stoker Class dragon.
 * The Hobblegrunt is similar to the Mood-Dragon in the books.
 * According to Fishlegs' Dragon Stats, Hobblegrunts are, during the time of How to Train Your Dragon 2, the newest addition to the Stoker class.
 * The Hobblegrunt is considered a good luck dragon as it is able to predict things a split second before they actually happen.
 * In Rise of Berk, the Hobblegrunt is missing the frill on its tail and has an excessively long neck.
 * In the Book of Dragons, the Hobblegrunt was listed as Boulder class.
 * In Rise of Berk the Hobblegrunts eyes are completely white, this is a common mistake made by many people due to the fact that Valkas Hobblegrunt Gruff was the closest shot we got of the Hobblegrunt, when in fact white eyes are a feature unique to just Gruff due to his blindness, while usually Hobblegrunts have yellow eyes with pupils.