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.
Spider - Man. Bringing the web - slinging superhero into the world of Final Fight would be unexpected. His ability to swing around the city streets and his spider - sense would make for some exciting battles against the Final Fight enemies. He could also use his webs to trap the villains in a different way compared to the normal Final Fight combat.
Wall - E could be a very unexpected character. He's from a post - apocalyptic world where he's all alone collecting trash. In an Ever After High crossover, he could land in the school's garden and start cleaning up. The students would be so confused by this little robot. But he could also teach them about the importance of taking care of the environment, which is something not really focused on in the fairy - tale world of Ever After High.
I think Groot from Guardians of the Galaxy is already quite an unexpected character in the Infinity War story. But if we want to be even more out - there, how about Snoopy from the Peanuts? Imagine Snoopy flying his doghouse into the middle of the battle against Thanos and using his imagination - powered antics to distract the villains. It would be a really wacky and unexpected addition.
The Doctor from Doctor Who. He could bring his time - traveling TARDIS into the Justice League's universe. His wits and knowledge of different times and places could be a huge asset in solving a mystery that the Justice League is facing, and his alien nature would add an interesting element.
I think Groot from Guardians of the Galaxy would be really unexpected. Imagine a Hogwarts teacher trying to communicate with a talking tree. It would be hilarious and full of misunderstandings at first. But then they could find a way to work together, maybe Groot could use his strength to help with some physical tasks around Hogwarts in a really unique way.
I think Gizmo from the Teen Titans could be really unexpected. He's used to dealing with high - tech and more colorful villains. Throwing him into Arkham Asylum, with all its dark and gritty atmosphere and dangerous inmates, would create a really interesting dynamic. He could try to use his gadgets to either escape or try to take over the asylum, which would be hilarious considering the much more menacing villains there.
Gandalf from 'The Lord of the Rings'. His magic and wisdom could add a new dimension to the story. He could help the X - Men in their fight against Apocalypse, perhaps using his magic to counter some of Apocalypse's powers or providing strategic advice.
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 Care Bears. It would be really unexpected to see the cute and cuddly Care Bears in the dark and violent world of Twisted Metal. Maybe they could be there to try and bring some peace and love, but end up getting caught in the crossfire between the Twisted Metal drivers.
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.