Grunkle Stan and Toriel could be an interesting pairing. Grunkle Stan is a bit of a con artist but has a good heart deep down. Toriel is a motherly figure. They could have some great interactions where Toriel tries to get Stan to be more honest and kind, while Stan might try to find some business opportunities in the Undertale world. It would be a clash of personalities but also a chance for growth for both characters.
I think Tommy and Dipper would be a really interesting pairing. Tommy is the fearless leader among the Rugrats, and Dipper is always eager to solve mysteries in Gravity Falls. They could combine their skills and curiosity to explore new areas in Gravity Falls or figure out some strange happenings. Another cool pairing could be Angelica and Pacifica. Angelica is used to being bossy, and Pacifica has her own airs, so it would be fun to see them butt heads or, surprisingly, become friends.
Alphys and Iron Man. Alphys is a scientist in Undertale who is a bit of a klutz but also brilliant. Iron Man is a genius inventor in Marvel. They could collaborate on some crazy technological inventions. Alphys could learn a lot from Iron Man about presenting herself more confidently, and Iron Man could be intrigued by Alphys' unique approach to science that comes from the Undertale world.
I think Leonardo and Papyrus would make an interesting pairing. Leonardo's leadership and discipline could contrast with Papyrus' more naive and enthusiastic nature. They could learn from each other, like Leonardo teaching Papyrus some ninja moves, and Papyrus showing Leonardo how to have more fun. Another great pairing could be Donatello and Alphys. They are both the 'tech - smart' characters in their respective universes. They could collaborate on some crazy inventions that combine Undertale technology and Turtle - made gadgets.
I think Freddy Fazbear and Toriel would make an interesting pairing. Freddy is this big, imposing animatronic, while Toriel is a motherly figure. Their interactions could be really cool, like Toriel trying to understand what Freddy is and Freddy being a bit confused by Toriel's kindness.
Ruby and Frisk would be a really interesting pairing. Ruby is full of energy and determination, and Frisk has that unwavering kindness. They could learn a lot from each other, especially in terms of how they approach difficult situations and make decisions.
Another interesting pairing would be Ron and Papyrus. Ron is known for his loyalty and his love for food, and Papyrus is this enthusiastic skeleton who loves cooking and making friends. They could bond over food, with Ron introducing Papyrus to some wizarding world delicacies like Butterbeer and Pumpkin Pasties, and Papyrus showing Ron his 'Spaghetti Surprise'. Their friendship could also be a source of comic relief in a more serious crossover story.
Frisk and Dave Strider would be an interesting pairing. Frisk is all about kindness and determination in Undertale, while Dave is this cool, sarcastic guy from Homestuck. Their different personalities could lead to some really fun interactions, like Dave trying to be all cool while Frisk just goes about their business of being kind to everyone.
Definitely Star and Dipper. Star is this wild and powerful magical girl, and Dipper is the curious and knowledge - seeking boy. They could share their knowledge about the different kinds of magic and mysteries in their respective worlds. For example, Star could show Dipper some of her spells, and Dipper could introduce Star to his research on the strange happenings in Gravity Falls.
Definitely Steven and Dipper. Steven is so open - hearted and has a positive outlook, while Dipper is more skeptical and curious in a different way. Their different personalities could lead to some really interesting exchanges as they try to understand each other's worlds.
The interactions between Ford Pines and Danny's parents could be fascinating. Ford, with his vast knowledge of the strange and supernatural, might be intrigued by Danny's parents' attempts at ghost hunting, even if their methods are a bit more primitive compared to his own scientific investigations. Meanwhile, Danny's parents might be in awe of Ford's knowledge and the things he has discovered in Gravity Falls. This could lead to some comical moments as well as some interesting exchanges of ideas about the nature of the supernatural.