Maybe the Loud siblings could be transported to the TMNT universe. The boys would be fascinated by the Turtles' ninja skills and gadgets, and the sisters could use their own unique skills to help the Turtles in their fight against the Foot Clan. For example, Lola could use her pageant charm to distract the bad guys, while Lincoln could bond with the Turtles over being part of a big group.
The Turtles could interact with the Loud family by sharing their knowledge of martial arts. For instance, Raphael could teach Lincoln some self - defense moves. In return, the Louds could introduce the Turtles to normal family activities like having a family dinner or playing board games.
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.
Another plot could involve a love triangle among the Loud siblings' friends. They all end up at the Loud House often, and the love triangle causes some tension. But through various events at the house, like parties or family outings, they start to understand each other better and resolve their differences in a really sweet way.
One idea could be that the Loud siblings discover they have magical abilities and are sent to Hogwarts. Lincoln could be sorted into Gryffindor for his courage in dealing with his large family. Another could be that a wizard from the Harry Potter world visits Royal Woods and gets involved in the chaos of the Loud family. Maybe they help the family solve a mystery using magic.
One idea could be that Spongebob and Patrick end up in the Loud House world. They could be really confused by all the human stuff and the big family. Maybe they try to make a Krabby Patty in the Loud House kitchen but use the wrong ingredients and chaos ensues.
One idea could be a crossover with another popular animated show. For example, the characters from 'Loud House' could end up in a different universe where they have to use their unique skills from 'No Such Luck' to survive. Maybe they meet characters who have similar family dynamics but different challenges.
One idea could be that the misfortunes from 'No Such Luck' somehow cross over into an alternate universe in the crossover. For example, Lincoln's bad luck could start affecting the other characters from the crossover world in strange ways, like causing their gadgets to malfunction.
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.
In this crossover fanfiction, the Hulk's strength could be used to help the Loud family in a big way. For example, there could be a natural disaster about to hit Royal Woods, like a huge flood or an earthquake. The Hulk, with his superhuman strength, could hold back the floodwaters or stop the shaking ground. Meanwhile, the Loud kids could be helping the townspeople evacuate. It would be a story of how two different universes come together to save a town.
One idea could be a time - travel plot where a character from the Loud House goes back in time and has to deal with changes in the family's history. Another could be a 'what if' scenario, like what if Lincoln had a different set of sisters. Maybe he could have all older sisters and the story could explore how that dynamic changes things.