One interesting crossover could be the characters from Gravity Falls ending up in the world of MLP. Maybe Dipper and Mabel could meet Twilight Sparkle and her friends. They could go on adventures together, like exploring the Everfree Forest in MLP's world. Dipper's love for mysteries might lead him to study the magic in Equestria.
Well, in a Gravity Falls x MLP fanfic, we might see Bill Cipher causing chaos in Ponyville. The ponies, with their magic, would have to figure out how to stop him. And the Mane Six could team up with the Pines family. For example, Rainbow Dash and Dipper might work together, with Rainbow Dash using her speed and Dipper using his smarts to solve problems.
A great crossover idea in a Gravity Falls x MLP fanfic could involve the Weirdmageddon from Gravity Falls spreading to Equestria. The ponies would be faced with the strange and dangerous creatures from Gravity Falls. The Elements of Harmony could be used in new ways to combat the chaos. And the characters from both shows would have to learn from each other. The ponies could teach the Gravity Falls characters about friendship and harmony, while the Gravity Falls crew could show the ponies how to face really strange and otherworldly threats.
Chapter 81 is the strongest chapter-level answer because it starts from Qi Tianyu, who chose curry beef rice, received a piece of curry and a... and follows through on The summer on the Southwest Plateau is no joke; the sun at three o'clock....
The best chapter pointer here is Chapter 107, "Are You Really Going to Participate in That Variety Show?". It opens with On the plane, when He Yun had taken off his mask and greeted her... and closes on Although Su Yinwan's recent change in temperament had been hard for her to....
The best chapter pointer here is Chapter 72, "Jiang Li Resembles an Early Capitalist". It opens with Jiang Yan was still griping when suddenly a fair hand reached out beside... and closes on Think about it." Jiang Yan fell silent..
If you want the clearest chapter reference, go to Chapter 92. Early on, Jiang Li, lightened from any task, had plucked a few leaves from the...; later, the chapter leans on She then produced a book from somewhere and began flipping through it on....
Look to Chapter 97 for the clearest answer. It begins with Suddenly, Jiang Li's livestream room was packed with people, and the..., keeps building through [I came from Weibo's trending topics, is Master Jiang really that awesome?, and lands on And you believe what she says?.
The best chapter pointer here is Chapter 74, "Ordinary People". It opens with Having seen Jiang Li's ID before, he knew that this person named Shiguang... and closes on The man's phoenix eyes narrowed slightly, he looked at the girl sitting....
Chapter 70 is the strongest chapter-level answer because it starts from So, under the curious gazes of everyone, Jiang Yan strutted up with his... and follows through on He Yun was also surprised as he looked towards Jiang Li..
Look to Chapter 103 for the clearest answer. It begins with Jiang Yan looked at Zhao Lang with suspicion, eyeing the dark substance in..., keeps building through It's not going to make my face fester, is it?" Zhao Lang smiled, "Do I..., and lands on Jiang Yan felt deep guilt welling up inside.
Look to Chapter 87 for the clearest answer. It begins with Luckily, at that time, Jiang Li had already taken her pot of stinky..., keeps building through But all this still didn't escape the high-definition camera., and lands on I'm driven crazy by him every day.] [+1 from above!.
If you want the clearest chapter reference, go to Chapter 77. Early on, Wen Jiaojiao's reminder calmed Shu Yan down.; later, the chapter leans on Indeed, the wild mushrooms on the Southwest Plateau were complex in....