Well, it could be Twilight Sparkle and Spongebob. Twilight is the intelligent and studious one in My Little Pony. She would be intrigued by Spongebob, who is clearly a very different kind of creature from Equestria. Spongebob, on the other hand, would be in awe of Twilight's magic and knowledge. Their first meeting might happen when Spongebob is exploring the library in Ponyville that Twilight often frequents. She would start asking him questions about where he came from and what his world is like.
Another possibility is that Patrick and Fluttershy would interact first. Patrick's simple - mindedness could be a contrast to Fluttershy's shyness. Patrick might not understand why Fluttershy is so quiet at first, but then he would do something silly like try to share his love for rocks with her. Fluttershy would be a bit startled by Patrick's forwardness but then she would see his kind heart. And so, their first interaction would be this sort of comical and gentle encounter.
Probably Spongebob and Twilight Sparkle. Spongebob is always curious and eager to explore new things, and Twilight is the most studious and open - minded of the ponies. So when Spongebob arrives in Equestria, Twilight would be the one most likely to approach him first, wanting to learn about this strange new creature. And Spongebob would be happy to talk to her because she seems friendly and intelligent.
Probably Goku and Twilight Sparkle. Twilight is the smart and curious one. She would be the first to approach Goku out of scientific interest, wanting to understand where he came from and what his powers are all about.
One possible plot could be that Spongebob somehow gets transported to Equestria. He befriends Pinkie Pie first because of their similar energetic natures. They start having a party together, and Pinkie Pie shows Spongebob around Ponyville. Then, they might encounter a problem like a mysterious spell that's making all the ponies sad. Spongebob, with his positive attitude, tries to help the ponies cheer up and along the way, he meets Twilight Sparkle who teams up with him to find a way to break the spell.
I think Pikachu and Fluttershy would be likely to interact first. Pikachu is curious and friendly, and Fluttershy is gentle and kind - hearted. Their personalities would make them approach each other easily.
Probably Naruto and Twilight Sparkle. Twilight is the intelligent and curious one in the My Little Pony world, always eager to learn new things. Naruto, with his unique ninja abilities, would be something completely new for her. She would likely approach Naruto first to find out more about him.
Happy from Fairy Tail and Pinkie Pie from My Little Pony. Happy is a fun - loving and friendly cat - like creature, and Pinkie Pie is the life of the party. They would likely find each other immediately and start having a great time together, sharing jokes and treats. Pinkie Pie might even teach Happy some of her party - planning skills.
In battle situations, they could form alliances. If there is a big threat that endangers both their worlds, like an evil force that can travel between dimensions. The Autobots and the ponies could fight side by side. The strong and powerful Transformers could provide brute force, while the ponies use their magic to support and strategize. For instance, Rainbow Dash could use her speed to distract the enemy while a Transformer attacks from the side.
In fanfiction, the characters could also interact on an emotional level. Maybe Peter Parker (Spiderman) is feeling down and the ponies, with their positive and friendly nature, cheer him up. Or a pony could be in trouble and Spiderman comes to the rescue, and in the process, they form a bond. The ponies could teach Spiderman about the power of friendship, which is a central theme in My Little Pony, and Spiderman could teach them about courage and responsibility.
Doctor Strange and Ajak. Doctor Strange is well - versed in the mystic arts and Ajak has a lot of knowledge about the Eternals' history and their connection to the Celestials. Their knowledge areas could intersect, and they would likely be the first to start sharing information. Maybe Strange senses some strange energy related to the Eternals and approaches Ajak to find out more.
Obviously, Winona would be one of the main characters. And probably some of the well - known My Little Pony characters like Twilight Sparkle or Rainbow Dash. Since Winona is on their hips, they are likely to be central to the story as well, as they would be the ones interacting with Winona and involved in whatever events take place.