Probably Genie from Aladdin. Genie is all about granting wishes and his larger - than - life personality. In a Frozen crossover, he could offer to grant Elsa a wish, like making her ice powers more controllable or finding her a true love in a really over - the - top way. It's not a combination you'd think of right away.
The Cheshire Cat from Alice in Wonderland. His mischievous and mysterious nature would be very different from the Frozen world. He could appear and disappear in Arendelle, confusing the characters. Maybe he'd lead Elsa on a strange journey through some kind of ice - themed Wonderland - like place, which would be a really unique crossover.
However, All Might also has to be considered. His One For All Quirk gives him superhuman strength, speed, and durability. If he were to face off against Elsa, he could potentially use his physical abilities to break through her ice. But Elsa's power is more versatile in terms of creating different ice formations and manipulating the environment.
Mario. The plumber from the Mushroom Kingdom in a crossover with Final Fight would be quite a shock. However, his acrobatic jumps and ability to use power - ups could add a unique element to the fanfiction. He could jump on the heads of the Final Fight thugs or use a fire flower to defeat them in an unorthodox way.
A crossover with Moana might be interesting too. Moana could take Elsa and Anna on a journey across the ocean in her boat. Elsa could use her ice powers to create paths or structures on the water. They could face challenges like sea monsters and learn from each other's different ways of life.
Jon Snow would also be a great addition. His journey from being a bastard to a leader in Game of Thrones could be paralleled in the world of Frozen. He could learn from Elsa about controlling his powers (if we assume he has some new ice - related powers in this crossover) and in turn, teach the people of Arendelle about loyalty and sacrifice, which are values he has held dear in Westeros.
I think pairing the Dragonborn with Elsa would be very interesting. The Dragonborn has all these combat skills and knowledge of magic, while Elsa has her powerful and sometimes uncontrollable ice magic. Their interactions could range from the Dragonborn trying to help Elsa better control her powers to them teaming up against a common enemy, like a powerful ice - themed demon that is drawn to their combined ice magic.
One of the most interesting pairings would be Hawkeye and Sven. Hawkeye could ride on Sven while using his archery skills to fight enemies in the frozen landscapes. It would be a unique combination of mobility and ranged attacks. Another good pairing is Loki and Hans. They both have a devious side and could plot together to cause trouble in the crossover. However, the Avengers and the Frozen heroes would have to work together to stop their evil plans. And Scarlet Witch and Elsa could also be a fascinating pairing. Scarlet Witch's powers of manipulation and Elsa's ice powers could create some really cool and powerful combinations when they team up against the common enemies.
I think Squidward from Nicktoons and Courage the Cowardly Dog from Cartoon Network would be quite unexpected. Squidward is always so grumpy and pessimistic, while Courage is, well, cowardly but also very kind - hearted. Their interactions would be really strange and comical.
Plastic Man. Imagine Wolverine's no - nonsense attitude combined with Plastic Man's goofy and elastic nature. They would be a very odd couple. Wolverine might be frustrated by Plastic Man's antics at first, but then they could find that their abilities complement each other well in a fight. For example, Plastic Man could wrap around Wolverine to protect him while Wolverine attacks the enemy with his claws.
Tsukune and Rukia could be an unexpected pairing. Tsukune is a normal human in a world of yokai, while Rukia is a Soul Reaper from the world of Bleach. Their different backgrounds and powers could lead to an interesting dynamic. Rukia could teach Tsukune some combat skills, and Tsukune could show Rukia the more light - hearted side of the yokai world.
I think Haru from Free! and Kuroko from Kuroko no Basuke would be an unexpected pairing. Haru is so focused on swimming and his own world of water, while Kuroko is all about basketball and his quiet, yet strategic play. But if they were paired together, Kuroko's calm and calculated nature might complement Haru's single - minded focus. They could learn from each other's dedication to their respective sports.