White dragons are the weakest and the most feral of the classic chromatic dragons. Though dimmer than other dragons, they are still powerful enough to overwhelm most humans and have good long-term memories.
Goomy may be undeniably cute, but it's incredibly weak in nearly every measurable metric. In fact, the Pokedex states in multiple Pokemon games that it is the weakest Dragon-type ever recorded.
Lemures aren't just the lowest class of devil in D&D, but one of the weakest monsters in the entire game. While lemures may be immune to fire and poison, their pitiful Armor Class of 7 allows characters of all forms to land blows against them with ease.
The rarest of the metallic dragon types, the platinum dragon is believed to also be the most powerful. The species is so rare that scholars only know of one in existence, Bahamut.
However, true dragons fall into the two broad categories of chromatic and metallic dragons. The black, blue, green, red, and white dragons are selfish, evil, and feared by all. So, by canon alone, no, they can not be converted to good.
The Blue Dragon (Dungeons & Dragons) is a type of dragon in the Dungeons & Dragons universe. It is an evil-aligned chromatic dragon.
As we know, Vhagar is the last surviving dragon of Aegon the Conqueror's Conquest of Westeros. She was ridden by Visenya Targaryen, and, after her first rider's death, she spent 29 years by herself, with no one mounting her.
The character appears in the first edition Monster Manual (1977). In this book, the Platinum Dragon was given the personal name Bahamut. He was also identified as a lesser god for dragons in the book Deities & Demigods (1980).
Klauth, also known as Old Snarl, was supposedly one of the eldest dragons alive who had not been turned into a dracolich.
Monsters with a printed Level of 0 instead have a Level condition that treats their original Level as a different value. In the OCG and TCG, monsters' original Levels can range from 1 to 12, with a monster's original Level usually providing a rough indication of how powerful it is.
While Vecna from Stranger Things boasts impressive proficiency in mind control and psionic magic that makes him at a potentially world-ending threat, Vecna from Dungeons & Dragons literally ascended to godhood, cementing his place as one the most powerful magic users in existence - a multiversal threat.
So now we know that Skitterbugs is the fastest dragon in the How To Train Your Dragon franchise.
Toothless is incredibly physically adept in many respects. We learn that the Night Fury is one of the fastest dragons out there, clearly the fastest dragon species available on Berk itself. Not only is he fast, but he's incredibly dexterous, able to execute very complicated motions back-to-back flawlessly.
The most powerful of the chromatic dragons, red dragons are physical powerhouses. While they often lack tricks or unique abilities, they carry the day with their immense might and devastating fire breath.
Shenlong, "god dragon" or "divine dragon", s a spiritual dragon from Chinese mythology who is the master of storms and also a bringer of rain. He is of equal significance to other creatures such as Tianlong, the celestial dragon.
Vhagar, almost two centuries old and the strongest dragon alive, took a fatal bite out of Arrax, killing him and his young rider Prince Lucerys "Luke" Velaryon (Elliot Grihault).
Balerion - Ridden by Aegon the Conqueror
Named after an ancient god of the Valyrian Freehold, Balerion was born in Valyria and was one of the dragons that Aenar Targaryen brought with him when he fled to Peyredragon to survive the Doom of Valyria. He was ultimately the last dragon to see the Freehold at its peak.
The Lycanwing is one of four "mythical" dragons, with the other three being the Boneknapper, the Smothering Smokebreath, and the Foreverwing. Of the four, it is the only one that has no proof of its existence. It is unknown why the Lycanwing is in the Dragon Eye, even though it doesn't exist.
Ichneumon. Ichneumon are legendary creatures closely related to weasels and other mustelidae, and are one of the very few magical creatures capable of causing any trouble for dragons. Most prominently, Ichneumons are known for actually managing to kill them.
Balerion died of old age in 94 AC during the reign of King Jaehaerys I Targaryen, around two hundred years old.