The Princesses, Celestia and Luna, are likely to be part of it. They might be the ones with the knowledge or power to help Twilight. Celestia could offer her wisdom on how to control this new and dangerous ability, while Luna might use her connection to the night and dreams to figure out if Twilight is under some sort of spell.
The plot might involve Twilight being cursed or tricked into this 'eats the everything' state. She might start by accidentally consuming small things like flowers or books, which gradually grow into bigger things. And as she eats more, it affects the balance of the world around her, causing her friends to worry and try to find a way to reverse it.
Obviously, Edward himself is a central character as he is the one being wrongly blamed. Bella would also be involved as she is closely associated with Edward in the Twilight series. His vampire family, such as Alice, Jasper, Emmett, Rosalie, Carlisle and Esme, would likely be part of the story too. They would either be trying to help him clear his name or be affected by the false blame in some way.
Well, Naruto is obviously one of the main characters since it's in the title. He's the one doing all the eating. There might also be his friends like Sasuke and Sakura. Sasuke could be annoyed by Naruto's eating habits, while Sakura might be worried about the effects of all that eating on Naruto's health.
Rukia could also be in the fanfiction. Given their close relationship, she might be the first one to notice something is off with Ichigo. She could be the one trying to keep him out of trouble or scolding him for getting drunk in the first place.
It could be Discord. He loves chaos and might think it's fun to kidnap Twilight and see how her friends react. He could also be after her knowledge of magic to cause more mischief in Equestria.
Alice and Jasper could also be involved. Since they are both vampires and part of the Cullen family, an arranged marriage might be used to strengthen their bond within the coven or to establish some sort of connection with another vampire group. And Alice's visions could add an interesting twist to the story of an arranged marriage, as she might see the future implications of it.
Definitely Harry Potter himself. He's the central character in his own series, so it's likely he'd be involved in any crossover. Hermione Granger could also be a key character as she's smart and curious, and would be interested in learning about the 'Twilight' world. From 'Twilight', Edward Cullen is an obvious choice. His brooding nature and unique abilities would make for interesting interactions with the 'Harry Potter' characters. Also, Jacob Black could be involved, especially when it comes to the 'imprint' aspect as he has his own story arc related to that in 'Twilight'.
Well, Bella and Edward are almost certain to be involved. In Twilight, they are the central couple. In a fanfiction with this title, their relationship could be further explored, especially if something happened to Bella while she was sleeping that affected their bond.
Pepper Potts would probably be involved. She might be worried about Tony's new obsession with the Infinity Stones and try to keep him grounded. Happy Hogan could also be there, providing some comic relief and practical support.
The other Slytherin students are very likely to be involved. Some might side with Draco, while others might see his punishment as an opportunity to gain power within the Slytherin hierarchy. Pansy Parkinson, for instance, might react in different ways depending on her relationship with Draco at the time of the punishment.