Lydia Martin would also be a good character to include. She's smart and powerful, and her relationship with Stiles could be further explored in the context of the crossover. Her banshee abilities might come in handy when dealing with any new threats in the crossover world.
A plot could involve Stiles' real family crossing over into a world where they are all superheroes. Stiles has to adjust to having powers and his family has to deal with the new responsibilities. There could be a villain that targets Stiles' family specifically because of their newfound powers, and they have to work together to defeat the bad guy.
One common theme is the clash of different worlds. For example, when Stiles crosses into a different universe like the Vampire Diaries' world, his normal life from the Teen Wolf universe clashes with the supernatural politics and rules of the new world.
Well, if you're doing a crossover with 'Pokémon', Ash Ketchum would be a great addition. He could help the Rugrats understand the world of Pokémon and they could go on a Pokémon - hunting adventure together. Another good character for a crossover, say with 'Digimon', would be Tai Kamiya. He could show the Rugrats how to interact with Digimon. And for a crossover with 'Ben 10', Ben Tennyson could be included. He could use his alien forms to protect the Rugrats in dangerous situations.
There's 'Stiles and the Winchester Brothers'. This fanfiction crosses over Stiles with the Supernatural world. Stiles' character really stands out as he tries to navigate the world of hunting and the Winchester family's dynamic. It has some really interesting plot twists and great character interactions. For example, his banter with Dean and Sam is both humorous and engaging.
The parents should be included. Their parenting styles and reactions to the girls' different situations can add depth. Mrs. Rooney's attempts to keep the family together while dealing with Liv's Hollywood drama and Maddie's sports - related issues can be really interesting. Mr. Rooney's comical yet supportive role can also be explored further. Additionally, Willow from Liv's world could be a good character to bring in. She could befriend Maddie and introduce her to the more glamorous side of Liv's world, causing Maddie to have a new perspective on her sister.
Shadow would be a great addition. His brooding nature and powerful combat abilities would add an interesting dynamic. He could be suspicious of Infinite at first and be in conflict with Sonic about whether to trust him or not. And then there's Knuckles, who could guard some important location or object that is related to the crossover event, like a powerful chaos emerald that is causing the dimensions to cross.
Sherlock Holmes is a great choice. His deductive skills would contrast well with Kaito Kid's thieving skills. Another good one is Lupin III. They are both master thieves, and a crossover between them could be full of interesting heist scenarios. Conan Edogawa would also be interesting. Since he's always trying to catch Kaito Kid in the original series, a crossover could explore new dynamics between them.
Ryder is a must - include character. He's the leader of the Paw Patrol, so he can be the one to initiate the crossover and bring the different groups together. Also, Chase would be great as he's very brave and good at following rules, which could be useful in a crossover situation.
The Precursors are very important in the Jak and Daxter universe, and including them in a crossover fanfiction could add a whole new level of depth. They could be the key to understanding the new world they cross into, or perhaps they have a hidden agenda that Jak and Daxter have to figure out. Also, the Metal Heads could be included in a more action - packed crossover, where they pose a threat not only in their own world but also in the crossed - over world.
Definitely Naruto and Hinata as the core. But Iruka sensei could be a wonderful addition. He was Naruto's first teacher and could offer wisdom and guidance in this new, strange crossover world. Then there's Shikamaru. His intelligence and strategic thinking would be invaluable. He could come up with plans to deal with any threats that arise in the fanfiction, and his laid - back yet perceptive personality would create interesting interactions with the other characters.