Well, it could be that one of the FNAF animatronics gets sent to the Loud House world by accident. Let's say Freddy. Freddy then starts to interact with the family. He might mistake the Loud family for the pizzeria staff. Lincoln and his sisters would have to work together to either fix Freddy and send him back or find a way to co - exist with him. The younger siblings like Lily might be curious about Freddy rather than scared at first, which could add a cute element to the otherwise potentially spooky crossover.
I think Lynn could also survive. She's tough and athletic. If it came down to it, she could probably outrun the animatronics or even fight them off physically. She's not one to back down from a challenge, and in a FNAF - like scenario, her physical abilities would be very useful. However, she might need to learn to be more strategic as the animatronics are not your typical opponents.
One idea could be that the Loud family somehow gets transported to Gotham City. Lincoln could befriend Robin and they team up to solve a mystery that involves both Gotham and Royal Woods' villains. Maybe the Joker has a plan that involves stealing a special item from Royal Woods, and the Louds have to work with Batman to stop him.
One example could be a crossover where the characters from 'The Loud House' meet the characters from 'IT' in a strange town. Maybe the Loud siblings end up in Derry and have to face Pennywise together with the Losers Club. It could be interesting to see how the different personalities from 'The Loud House' react to the terrifying situations in 'IT'.
In such a fanfiction, the characters from 'The Loud House' could find themselves in Spyro's world. Maybe Lincoln Loud might team up with Spyro to fight some common enemies. For example, they could face a villain who is causing chaos in both their worlds. The Loud siblings' unique personalities could add a new dynamic to Spyro's adventures.
If you're doing a crossover with 'Scooby - Doo', Scooby and Shaggy are must - includes. They could bond with the Loud family over food and then get caught up in a mystery in Royal Woods. Velma could use her smarts to solve the mystery, and Fred could lead the way with his trap - making skills. Daphne could also befriend the Loud sisters and add some charm to the story.
A cool plot for 'the loud house crossover fanfiction' might involve a crossover with 'My Little Pony'. The ponies could come to Royal Woods, and the Loud sisters could be fascinated by their magic and cuteness. Lincoln might have to figure out how to get the ponies back to Equestria while also dealing with his sisters' excitement. Or perhaps the Loud family travels to Equestria and has to adapt to a world ruled by ponies.
First, focus on the characters' personalities. For example, make use of the Loud siblings' diverse traits. Then, blend the horror elements of 'IT' with the family - centric theme of 'The Loud House'. Maybe have the kids from 'The Loud House' use their family bonds to overcome Pennywise's fear - inducing tactics.
To write a great Loud House x Batman crossover fanfiction, focus on the interactions. Let the differences between the two groups create interesting dialogue and situations. The Louds' humorous and family - centered dynamic can contrast with Batman's solitary and serious nature. Also, don't be afraid to introduce new elements or twists. Maybe there's a secret connection between one of the Louds and a character from Batman's universe that gets revealed during the story. And always proofread and edit your work to make sure it flows well.
Another plot might involve a character from the 'bad luck' side of the crossover coming to the Loud House world and bringing their bad luck with them. This could disrupt the normal family dynamics. The Loud siblings would then have to figure out how to get rid of the bad luck and restore order. They might try all sorts of wacky plans, like using their own unique skills and talents in a new way to combat the bad luck.