Gobsucker

The Gobsucker is an original, Mystery Class dragon from the How to Train Your Dragon Live Spectacular that later appears in Dragons: Rise of Berk.

Official Description
"To help it take off, build speed, and even fly straight, this Dragon releases a blast of gas from behind. Needless to say; never sneak up on a Gobsucker! Let this dragon fight from afar. It's acid blasts may burn through enemies, but its back-gas-blast will destroy everyone else"

- Dragons: Rise of Berk

Egg
Gobsucker eggs are oval-shaped with stripes and small rock-like structures around their base.

Hatchling to Adult
This dragon is small in size. It has a small horn on their nose and a spiked crest on the back of its head. Their snout is broad. The Gobsucker's built is rather stocky and they have large, flat feet that resemble that of an elephant. Most Gobsuckers have stripes on their body and limbs and a pale underbelly.

Titan Wing
Titan winged Gobsuckers have pink head, wings and backs. On their back, legs and tail they have the same model of stripes but this ones are purple. They have more spikes on their heads and a lot on their backs. Their nasal horns grew as well as the talons on their wings.

Fire
Unlike most dragons, which emit fire from their mouths, scales (Monstrous Nightmare), or tails (Singetail), the Gobsucker shots flammable gases from its rear end. This fire does not simply serve the purpose of other dragon's fire, it helps the dragon fly straighter, faster and take off. This ability makes it hard to sneak up on a Gobsucker as anyone who approaches from behind will be a potential victim of the Gobsucker.

According to Gobber, this dragon's ability to fly is entirely dependent on the release of explosive gases from its rear end. As such, a Viking should never approach this dragon from behind.

Weakness
Gobsuckers cannot shoot any fire at someone unless they are behind them. Other than that the only attack they have is strength. Also, it can't fly if it is out of shots, and a downed dragon is a dead dragon.

How to Train Your Dragon Live Spectacular
Gobber first describes this dragon to the academy Vikings. It is later seen on the bottom of Gobber's chair. He probably uses this Dragon to move his chair around. Another Gobsucker is seen fighting with Vikings of the academy right before their first encounter with a Gronckle.

Dragons: Rise of Berk
The Gobsucker, along with it Titan form appeared in this game. Two more individuals, Muddlehunt and Gobstinker appeared too. Gobsuckers are mentioned to have normal fire in their battle description in Rise of Berk, however, this fire has never been seen as of yet.

Trivia

 * The Gobsucker slightly resembles a Rumblehorn.
 * The Gobsucker bears a strong resemblance to Boulder Class dragons such as the Gronckle, the Groncicle and the Hotburple, despite being a Mystery Class dragon.
 * The Gobsucker's legs are similar to that of an elephant.
 * Unknown Dragon 1 from How to Train Your Dragon 2 somewhat resembles a Gobsucker.
 * However, Rise of Berk kept the Gobsucker's original design, rather then using the design of Unknown Dragon 1, meaning it's definitely not the same dragon.
 * The Gobsucker is the second dragon species that had a specific individual appear in Rise of Berk before the dragon itself did, the first being the Catastrophic Quaken (Spikeback) and the third being the Triple Stryke (Sleuther).
 * The Gobsucker's ability to blast gas to take off is similar to the Assblaster from the third Tremors movie.