He is the most powerful dragon in Dragonball GT and he is destroyed by Goku with his ultimate spirit bomb(universal Genki Dama)
Like all evil dragons, Yi Xing Long was born from the dragon balls. When Bulma and Goku invoked Shenron, instead of appearing the good Dragon, came the evil dragon Black Dragon Smoke with a futile personality and he was rude. Black Smoke Dragon did not have any desire, but instead it gave rise to seven dragons full of negative energy, whose aim was the destruction of planet earth. One of these dragons was Yi Xing Long, the dragon of one star and the most powerful and feared enemy that Goku and the Z Warriors have ever known.
The main plot was not created by Akira Toryana. Dragon Ball GT and many of its new characters (including Yi Xing Long) were created by Daisuke Nishio and Osamu Kasai (directors of Dragon Ball GT) at the request of the Japanese animation studio Toei Animation.
Yi Xing Long has a personality only for destruction. When Yi Xing Long absorbs the dragon balls and he transforms into Omega Shenron (Super Yi Xing Long in Japanese), he calls himself the ultimate god of destruction. He has a personality much like the personalities of Frieza and Cell.
He is a cold character, arogant and he is very proud to show that he has a great combat power to Goku.
Here is a brief summary of the history of the character. He appears in the animated series Dragon Ball GT episode 57 to episode 63.
After killing the dragon of four stars (Suu Shenron) Li Shenron appears (the dragon of one star and also the leader of the evil dragons and the strongest). Li Shenron can control Goku ( Super Saiyan 4 form) without problems. Goku uses his most powerful technique, the Kamehameha increased 10 times. But Goku was defeated by Li Shenron. Goku would be killed by the dragon, but Gohan, Goten, Trunks and Uub appear (they save Goku). In an act of extreme difficulty, Goku asks his friends to pass the energy for it. Goku returns to the form of Super Saiyan 4, but this time with much more energy. Goku can defeat the dragon (Li Shenron is hit by a powerful blow). But this powerful coup from Goku was not enough to defeat Li Shenron. Li Shenron eats the dragon balls. Li Shenron becomes Omega Shenron. Omega Shenron acquires a unique power and wins easily. Goku (with no choice)
tries to commit suicide with the enemy in an explosion. However Vegeta appears. Vegeta becomes Super Saiyan 4 (Vegeta is using a machine with Blutz radius). Goku and Vegeta (both transformed into Super Saiyan 4) use the fusion. Omega Shenron was almost defeated, but the time of the fusion is over. After a long battle, Omega Shenron defeats Goku and Vegeta. Omega Shenron is destroying the Earth. However Goku appears. Goku decided to make the Genki-Dama (the Genki-Dama is made with the energy of all beings in the universe). The Genki-Dama universal is released and Omega Shenron is eliminated permanently forever.
Level of Physical Strength: Li Shenron has enormous physical strength. The physical strength of the Dragon is enough to defeat Goku (Goku Super Saiyan 4) without problems. After absorbing the power of dragon balls, Omega Shenron has a higher power (Omega Shenron is capable of fighting against the two characters - Goku and Vegeta (both transformed into Super Saiyan 4).
Level Speed: The level of speed Li Shenron is superior to all other characters in the Dragon Ball universe (with the exception of Gogeta (Super Saiyan 4). Li Shenron has speed to meet Goku and Vegeta without being detected.
Level of Durability: Li Shenron demonstrated exceptional durability. The Ki blasts from Vegeta (Super Saiyan 4) are inefficient. The most powerful technique of Goku (the 10x kamehameha) causes no harm to Li Shenron. After absorbing the dragon balls, the durability of Omega Shenron is higher than its previous form. Omega Shenron has enough durability to survive the most powerful attack of Gogeta - Big Bang Kamehameha.
Skills: Omega Shenron has all the skills of all evil dragons.
His skills include the ability to produce electric ray. He can increase the temperature of his body as the Dragon of four stars. He also can shoot streams of icy eyes with the ability to freeze the bodies of him opponents. The most important of all, Omega Shenron can replenish his body. Even if he suffers a powerful physical attack and his body is completely destroyed. He will rebuild again. The only way to defeat Omega Shenron is crushing his Ki from existence. As Goku did with the Universal Genki Dama.
Energy Manipulation: energy wave used to attack. Omega Shenron can use in many shapes, sizes and powers of destruction
Negative Karma Ball: This attack is the most powerful of Omega Shenron. This attack is a ball of negative energy (cylindrical form and red). Omega Shenron (in front of the torso) focuses the negative energy (negative energy comes from the dragon balls). According to Uub, the negaitive Karma Ball has a destructive power to annihilate an entire planet (Dragon Ball GT Episode 60). Omega Shenron has power to destroy the earth (Planet Buster).
Dragon Thunder: Omega Shenron is able to use a powerful electric attack. Vegeta tries to attack from behind, but Omega Shenron increases the size of the thorns and it punches Vegeta (during the process, Omega Shenron produces a powerful discharge of electricity.
Byosatsumakodan - Omega Shenron negative energy blasts used in the battle against Goten, Gohn, Trunks and Vegeta.
Yi Xing Long has few physical differences in the two transformations. Li Shenron has One-star Dragon ball on the forehead.
After absorbing the remaining dragon balls, the One-star Dragon ball appears in the trunk alongside the other six Dragon balls.
Li Sheron has two thorns on the trunk. After absorbing the Dragon Balls, the two thorns disappear from the trunk (but the thorns appear in the back (the horns are used to perform the Dragon Thunder ).
The images on the right side will help to notice the differences between the two forms.
Li Shenron is very intelligent. Li Shenron attacks the enemies with creativity. Omega Shenron tries to stop Goku and Vegeta (before they perform the fusion).
Omega Shenron aims to destroy the planet Earth with the negative energy flowing in him body (Omega Shenron is a being made of negative energy). According Rō Kaiōshin the negative energy of Omega Shenron can reach (and destroy) the Universe - even the Realm of Kaiōshins - Dragon Ball GT (Episode 63).
Trivia:Li Shenron was born from the wish that Kami-Sama made - Kami asked Shenlong to relive all the individuals/ beings Killed by Frieza and his henchmen on the planet Namek (the information is confirmed in the book Dragon Ball GT Perfect Files).