Typically, the owner of Dark Pegasus would be a main character. They are the ones who control the beyblade in battles and form a strong bond with it. This character could be a young and determined blader with a unique style.
One interesting story could be about Dark Pegasus evolving into a more powerful form. Maybe in the fanfiction, the beyblade gains new abilities through a series of intense battles and self - discovery. It could start with the owner of Dark Pegasus facing a seemingly unbeatable opponent. Through the bond with his beyblade, they unlock new powers and turn the tides of the battle.
Ryuga is often a very popular character in Beyblade Dark Nebula fanfiction. His powerful and somewhat mysterious nature makes him a great focus for many stories. He has the ability to draw readers in with his cool and often unpredictable actions.
Obviously, Barbie would be one of the main characters. And the pegasus, of course. There could also be other characters like Barbie's friends who might be worried about her when she disappears into the pegasus' world. Or there could be some magical creatures in the pegasus' world that play important roles, like a wise old owl or a mischievous fairy.
Well, Naruto is obviously one of the main characters. He brings his ninja skills and his unique personality to the beyblade story. Another could be Sasuke. He might be Naruto's rival in the beyblade battles as well, just like in the Naruto series.
Often, there's a young beyblade protégé who discovers he has some sort of vampire connection. For example, Tyson could be reimagined as having a vampire ancestor in some fanfictions.
Without reading the story, it's difficult to determine. But it might include a wizard or a wise old man who knows about Pegasus and helps the protagonist in their journey with the Pegasus. There could also be an antagonist, perhaps a jealous person who wants to steal the Pegasus away from the main character.
The main characters are Pegasus, of course, Bellerophon who tamed and rode Pegasus, and Medusa whose blood was the origin of Pegasus.
Sasuke could be one of the main characters. He might initially be skeptical about Naruto's new identity but then come to accept it and fight alongside him. Sakura could also be there, perhaps using her medical skills to help Naruto when he gets injured during his adventures related to his Pegasus heritage.
Obviously, Sophie is a main character. In many fanfics, her friends like Tyson or Kai might also be important characters. They often support Sophie in her beyblade journey, whether it's by giving her advice or competing against her to make her better.
Since I don't have detailed knowledge of 'beyblade ghost story', it's hard to say exactly. However, in the beyblade universe, there are often characters who are skilled at using their beyblades and have a strong sense of competition. So, in this 'ghost story' version, there might be characters like that who are also dealing with the spooky aspects related to the story.