In addition to the ones mentioned, Applejack could be a main character. Since she comes from an apple - growing family, she might supply the apples for the cupcakes. All these ponies, with their distinct personalities, come together in the fanfic to create a story around cupcakes, showing how their friendship is magic when it comes to baking and sharing these delicious treats.
The main characters would likely include Twilight Sparkle. She's very studious and might use her magic to help with cupcake - related tasks like getting the right amount of flour or sugar. Pinkie Pie is also bound to be a main character as she loves parties and cupcakes are a big part of parties in Ponyville.
Definitely Rainbow Dash. She could be involved in a plot where she has to race to get a special ingredient for the cupcakes in time. And Fluttershy too. Maybe she takes care of the animals that provide some of the ingredients, like the chickens that lay the eggs for the cupcakes. Rarity might also be there, using her sense of style to decorate the cupcakes in the most beautiful way.
Chapter 593, "Don't Look, It's a Bad Review!", is the clearest early answer because it turns Don's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The night was cool, and the two had just emerged from the chilly...
Chapter 831, "Brother, who do you like the most?", is the clearest early answer because it turns Shen Lan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Just as Jiang Shixu finished washing up and was getting ready to...
Chapter 472, "The Stream Dried Up?!", is the clearest early answer because it turns Guan Xiong's situation into a concrete plot event. It opens with Guan Xiong and his team had not had a proper meal in almost two or... and closes on Zhuola was the earliest to wake up..
Chapter 885, "Isn't This Wine?", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event.
Chapter 880, "Your sister has been taken to the station!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. Early on, Simply wearing it already helps dissolve part of the misfortune..
Chapter 468, "Joyously Receiving a Fainting Gift Pack", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Seeing a human, the wild boar became even more agitated, a massive...
Chapter 643, "Jiang Li Dominates the Trending Searches!", is the clearest early answer because it turns All's situation into a concrete plot event. It opens with Qi Tianyu joyously carried his construction to the side to wait for...
Chapter 764, "Has Someone from the Rong Family Arrived?!", is the clearest early answer because it turns Rong's situation into a concrete plot event.
Chapter 839, "Because There's a Good Show to Perform", is the clearest early answer because it turns Chinese's situation into a concrete plot event. It opens with But don't worry." Gu Qiang said, holding Shi Lei's hand, "The... and closes on But Rong Kexi wasn't the same..
Chapter 491, "A Cleaner Handling", is the clearest early answer because it turns Nina's situation into a concrete plot event.