Twilight Sparkle is really popular. She's smart and her magical abilities always add an interesting element to the story. Also, Sunset Shimmer is a favorite. Her backstory and her journey from being a bit of a villain to a hero make her a great character for fanfiction. Rainbow Dash is also popular, with her athleticism and competitive spirit fitting well into the Friendship Games setting.
Twilight Sparkle stands out as a popular choice. She often takes on a leadership role, which is great for stories set during the Friendship Games. Rarity is also a beloved character to feature. Her sense of style and her determination to be the best can lead to some interesting storylines, like creating the most amazing outfits for the games or having a friendly rivalry with other characters in the fashion aspect of the games.
Twilight Sparkle is a great character to feature. She's the founder of the School of Friendship, so she can be central to any story set there. Her intelligence and leadership skills can drive the plot forward. Rainbow Dash is also popular. Her competitive nature and loyalty to her friends can create interesting storylines, like when she has to compete in a friendship - based athletic event. Fluttershy is another good choice. Her kindness and ability to befriend even the shyest creatures can add a lot of heart to a fanfic, for example, if there's a new, scared animal at the school that she helps.
Ash Ketchum from Pokemon is a common character in these crossovers. He's a Pokemon trainer, and in a crossover, he could come to the world of MLP and start showing the ponies about Pokemon training. On the MLP side, Rainbow Dash is popular. Her adventurous and competitive spirit would make her eager to try out Pokemon battles or learn about different Pokemon species. So, a story with Ash and Rainbow Dash could be full of action and excitement.
Obviously Discord himself is a very popular character to feature. His chaotic nature and powerful magic make for interesting storylines. Pinkie Pie is also a common choice as her zany personality can either clash or complement Discord's chaos in really fun ways.
Well, Fluttershy is a character that many fanfiction writers like to include. Her gentle and kind nature can form really sweet friendships with human characters. For example, a human who is shy themselves might find comfort in Fluttershy's presence. Applejack is also quite popular. Her strong work ethic and loyalty can be a great influence on human characters in fanfictions. And of course, Spike, the dragon, is often in these fanfictions. His relationship with Twilight and his unique position in Equestria can add an extra layer of intrigue when combined with human interactions, like when he tries to understand human language or customs.
Natsu is often a popular choice. His fiery personality and powerful dragon - slayer magic make for exciting scenes in the Grand Magic Games. He's always eager for a fight and his growth throughout the games can be a great focus.
Cartman is often a popular choice. His devious nature makes for some interesting storylines in the Hunger Games setting. He could be plotting against everyone or trying to manipulate the rules. Stan and Kyle are also popular as they can represent different ideals in the Hunger Games. Stan might be more about survival and doing what's right, while Kyle could be fighting for justice within the game.
Sakura is also quite popular. Fanfiction often focuses on her development as a kunoichi, her relationships with Naruto and Sasuke, and how she overcomes her insecurities. There are many stories that give her more agency and power than in the original series.
Dr. Colosso, the family's pet bunny who is actually a supervillain, is another popular character. Fanfiction might explore his backstory more deeply or have him team up with other villains in a plot to finally defeat the Thunderman family.
JD Fenix is also quite popular. As Marcus's son, he has his own story arc in Gears 5 that can be expanded upon in fanfiction. You can explore his relationships with other characters more deeply, like his friendship or rivalry with other soldiers. Del Walker is another character that fans like to feature. His unique personality and his role in the team can lead to some interesting fanfic stories.
Jareth is by far one of the most popular characters. His mysterious and powerful nature makes him a fascinating subject. Writers can explore his backstory, his relationship with the Labyrinth, and his complex emotions.