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.
Luffy from 'One Piece' is a great choice. His carefree yet determined personality would contrast well with Ippo's more serious and focused nature. They could bond over their shared love for adventure and fighting for what they believe in.
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.
Definitely Balto himself. He's the main character and the centerpiece of any Balto - related fanfiction. Another popular character could be Steele. His antagonist role in the original Balto story makes for great conflict in crossovers. Also, Jenna is often included as she was an important part of Balto's story.
John Connor is often a popular choice. His leadership skills and importance in the Terminator series make him a great character to bring into other fictional universes. For example, in a crossover with a superhero world, he could be seen as a strategist working with the heroes.
Batman himself is obviously a must - include. His leadership and skills are central to the Batfamily dynamic. Also, Robin, especially Damian Wayne as his complex relationship with Batman adds a lot of drama. Nightwing is popular too, with his acrobatic skills and his own journey away from being Robin. Batgirl, like Barbara Gordon, is often included for her intelligence and fighting abilities. And Alfred, the ever - loyal butler, who often provides support and wisdom to the family.
In Ben 10 crossover fanfiction, many writers like to include Azmuth. As the creator of the Omnitrix, he has a wealth of knowledge and power. His presence can add a layer of depth to the story, especially when it comes to explaining the science behind the Omnitrix or helping Ben understand new alien forms. Also, Charmcaster is often included. Her magic abilities can create some interesting dynamics when combined with Ben's alien powers in a crossover.
Joker is definitely one of the most popular. His cool and mysterious demeanor makes him a great fit in various crossovers. Also, Morgana is often included as his sidekick. Another popular character is Makoto, with her strong - willed and intelligent personality.
Definitely Venkman. His sarcastic and witty personality can create great interactions in crossovers. For instance, if he were in a crossover with the X - Men, his humorous take on the mutants' powers would be hilarious.
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.