Ink!Sans is a popular pick. His creative and somewhat unpredictable nature can bring a lot of color (literally and figuratively) to a Glitchtale crossover. He could use his paint powers in the Glitchtale world in ways that no one expects. Also, Bete Noire from Glitchtale is a character that many fans like to include. Her relationship with other characters, especially her sister, can be explored in new and interesting ways when in a crossover situation.
Definitely Pikachu. Pikachu is one of the most recognizable Pokémon, and having it interact with Arceus in a crossover would be really cool. It could be like a small, cute Pikachu following around the all - powerful Arceus.
The Nurse is also great for crossovers. Imagine her in a world like Final Fantasy. She could use her healing abilities to help the party members. And then there's the Goblin Tinkerer. If he was in a Portal crossover, he might be interested in the advanced technology there and try to tinker with it, creating some interesting and comical situations.
Definitely Yu Narukami. He's the main character in Persona 4 and his leadership and strong Persona abilities make him a great addition to crossovers. Yosuke Hanamura is also popular. His comical nature and loyalty can add some humor and heart to the story. Chie Satonaka is another one. Her martial arts skills and determination are great traits in crossovers.
One popular character to include is Batman from DC Comics. The contrast between Batman's detective skills and gadgets and Raiden's superhuman powers would be fascinating. Another is Goku from Dragon Ball. Goku's love for fighting and his ability to reach new levels of power could lead to some epic battles with Raiden. And of course, Samus Aran from Metroid. Samus' armored suit and her exploration of alien worlds could be combined with Raiden's adventures in a unique crossover story.
The protagonist of the main Megami Tensei games, like the Demi - Fiend from Shin Megami Tensei III, is also a great choice. His unique backstory and abilities can add depth to any crossover story. He can bring his demon - slaying skills and knowledge of the Megami Tensei world into a new setting.
Jace Wayland is another great character. His charm and combat skills can add a lot to a crossover story. In a crossover with the Lord of the Rings, he could be seen as a kind of ranger, using his Shadowhunter skills to navigate Middle - earth and fight against the forces of Sauron.
If we consider a crossover with a superhero universe, characters like Superman could be interesting. His strength and moral code combined with the alpha stigma concept could create a really unique dynamic. He could interact with characters having alpha stigma in ways that test his own powers and beliefs.
Engineering characters from the Katana Fleet can also be great inclusions. They can use their technical knowledge to help or hinder the situations in the crossover. Maybe they have to fix a crucial piece of technology from the other series' world, or they might accidentally cause a problem while trying to adapt their own technology to the new environment.
The Emperor of the Rising Sun is a character full of potential in crossovers. In a crossover with the Star Wars universe, his unique leadership style and the advanced technology of his faction could create some really interesting storylines. He could be making deals with the Sith or trying to resist the Galactic Empire. And of course, Natasha Volkova, with her sniper skills, could be a valuable asset in a crossover, like in a battle against the Covenant in the Halo universe.
Cleopatra is another great character. Her beauty and intelligence made her a very influential figure. In a crossover, she could use her charm and wits to manipulate characters from different settings. Say, if it's a crossover with a superhero world, she might try to enlist the help of the superheroes for her own political gain.