Obviously, Sheldon himself. His mother would probably be there too. She's always been a big part of his life in Texas. And maybe his brother Georgie would also show up. They could have some brotherly bonding moments.
There's a good chance his friends from Pasadena might visit him in Texas. Penny, Leonard, Howard and Raj could all come and see how Sheldon is doing in his hometown. Their different personalities would create interesting interactions with the local Texans.
In this fanfiction, it could be that Sheldon tries to introduce some of his Pasadena friends to the Texas way of life. He could take them around to his favorite local spots, like the diner he used to go to as a kid. And there could be a lot of culture clash and humorous situations as a result.
Iruka sensei is almost certain to be in it. He has always been important in Naruto's life. Also, Sakura might be there. She could be one of the first to welcome Naruto or perhaps she might initially be a bit cold because of her past feelings for Sasuke. Other characters like Kakashi sensei could also make an appearance, guiding Naruto in his new life in Konoha.
Besides the main trio, Luna Lovegood could be a character in this fanfiction. Luna has a unique perspective on things, and she might be able to help Hermione in her journey of self - discovery. Also, some of the Slytherin characters like Draco Malfoy could be involved. Maybe Draco has some information or experiences that are relevant to Hermione's situation, and their interactions could add an interesting dynamic to the story.
Sasuke would be a likely character to appear. Since he and Naruto have a deep connection, Sasuke might cross paths with Naruto during his wanderings, either as an ally or an antagonist depending on the plot.
Sometimes, even antagonists from Hermione's past in the UK might make an appearance in the story. Maybe a Death Eater who escaped justice and is now also hiding in Australia. This would create a tense situation where Hermione has to deal with this old threat while also trying to build a new life in a foreign magical land.
Naruto is the key character as the title implies his movement to Suna. Gaara will most likely be a main character as well. His leadership in Suna and his connection to Naruto make him a natural choice. Additionally, some of the Suna elders or other important shinobi might be involved as secondary main characters, as they could be the ones who interact with Naruto and influence the events in Suna.
Since it's Harry who moves to Mystic Yaoi Falls, he will be central. But there could be other characters like a group of protectors of the falls. They might be initially suspicious of Harry but later become his allies. And there could be a mysterious figure who seems to have a connection to the strange happenings around the falls and Harry's arrival.
Obviously, Paul himself is the central character. His brother Reggie might also appear as he could be concerned about Paul's condition and offer support. Ash could be in it too. He might be someone who initially doesn't get along with Paul but then shows compassion because of his illness. And of course, Paul's Pokemon would be there, like his Torterra or Electivire.
Sakura's teammates from her original team could be likely characters. They would be worried about her and try to figure out a way to get her out. There could also be some local Kirigakure ninja who are curious about this outsider in their prison and interact with Sakura in different ways, either as friends or foes.
Sonic himself, of course. And his best friend Tails is very likely to be there. Tails is always by Sonic's side and would surely be there when Sonic is sick.