The evil dragons were created from all of the negative energy in each positive wish granted. The negative energy stored is a balance for the good energy that was used to make the wish. Most of the dragons have an ability & most of them had some kind of transformation.
» Black Smoke Shenron - In Dragon Ball GT, after the death of Super #17, Goku and his friends put together the 7 Dragon Balls. Instead of Shenron appears a black dragon, that represents the negative energy accumulated for many years (because the Dragon Balls use positive energy). This Dragon is then divided into 7 evil Shenrons, each for every Dragon Ball.
» Syn Shenron - Syn is the ultimate evil power in the universe. Syn was born with the combination of all the evil energy given out by the corroded Dragon Balls making him the strongest of the dragons. Syn eventually absorbs all 7 Dragon Balls to become the awesome Omega Shenron giving him the powers of every Shadow Dragon. The Dragon Balls were used to restore life, but Syn has only one goal...the destruction of all life in the universe! Dragon of the 1 star ball.
» Haze Shenron - Haze Shenron is the Dragon of Pollution. He uses his powers to create a muggy fog that settles over the land and drains any person coming into contact with it of all their power and energy. He was born when Goku used the Dragon Balls to wish Bora back to life many years ago. Dragon of the 2 star ball.
» Eis Shenron - The Dragon of Ice, Eis Shenron, is Nova Shenron's brother. Eis Shenron joins the fight against Goku and even has him down and beaten. Just as the Dragon Balls have turned against their masters, Eis Shenron may find that turnabout is fair play. Dragon of the 3 star ball.
» Nuova Shenron - The Dragon of Fire, Nuova, was born when King Piccolo wished for youth when Goku was a child. With the power of the sun and of fire at his disposal, Nuova is more than a challenge for Goku. Things really get hot when Nuova's brother, Eis Shenron, joins in the fray! Dragon of the 4 star ball.
» Rage Shenron - Despite his small size, Rage Shenron carries a shocking power: electricity! He creates a slimy substance that draws the energy out of any object that it touches; the energy is then transferred to his body as strength. Rage Shenron was born when Goku wished himself back to life after Vegeta landed on planet Earth. Dragon of the 5 star ball.
» Oceanus Shenron - The Dragon of Water and Wind, Oceanus Shenron, dons the persona of Princess Oto, who the residents of a small fishing village worship as a god. When asked which wish she was born from, Princess Oto becomes angry and embarrassed. Dragon of the 6 star ball.
» Naturon Shenron - After Vegeta killed a large number of innocent people, a wish on the Dragon Balls brought them all back to life. In this way, Naturon Shenron was born. Possessing the power of Earth, he delights in causing earthquakes and watching cities fall before his power. Dragon of the 7 star ball.