Red is an obvious choice. He's the main character in the games, and his journey through the Kanto region can be further explored in fanfiction. Maybe tell a story about his training methods or his relationships with other trainers that weren't fully shown in the game.
Definitely Red. He's the iconic protagonist of the game, and there are so many ways to expand on his story. You could write about his post - game adventures or what he was thinking during his original journey.
Gary Oak is also popular. He can be portrayed as a more complex character in fanfiction. Maybe a story where he teams up with Ash against a greater threat, or a plot where we see his own personal growth and struggles as a Pokemon trainer in the context of the Yellow and Red games.
Red is definitely a popular character to feature. He's the main protagonist in the games, so many fanfictions revolve around his further adventures or his backstory. Another popular one is Pikachu, the iconic Pokemon. You can write all sorts of stories about Pikachu's relationship with Red or other trainers. And of course, Blue is often in fanfictions as well, as he's Red's rival and their dynamic can be explored in many ways.
Charizard is a very popular Pokemon to feature in a 'pokemon red and blue fanfic'. It's powerful and has a cool design. Misty, the water - type gym leader, is also a great character to include. Her feisty personality can add a lot of drama to the story. Another popular character is Brock, with his love for rocks and Pokemon. He can be a source of knowledge for the main character in the fanfic. Plus, Team Rocket's Jessie and James are always fun to have in a fanfic. Their bumbling attempts at stealing Pokemon can create some humorous situations.
Red is often very popular. He's the main character in the original games, so in fanfiction, people like to explore his adventures further, like his battles against powerful Gym Leaders in more detail.
Definitely Red and Green themselves. They are the iconic protagonists of the original games, so including them can add a lot of authenticity to the fanfiction. Also, Professor Oak is a popular choice as he is the wise mentor figure. And of course, Pikachu is always a fan favorite to include, whether as a main character's Pokemon or just making appearances throughout the story.
Red and Green themselves are often very popular. Red, being the determined and skilled trainer, and Green with his more strategic and sometimes cocky approach. Their dynamic as rivals - turned - allies (in some stories) is really appealing.
The Legendary Pokemon like Suicune, Raikou, and Entei can also be central characters. You could write a story about a trainer's quest to find and befriend these Legendary beasts. It could be a spiritual journey as well, as these Pokemon are often associated with certain elements and powers in the Pokemon lore.
N is definitely a popular character. His complex backstory and relationship with Pokemon make him an interesting choice. Hilbert or Hilda, the protagonists of the games, are also often featured. Then there's Ghetsis, the main villain, who can add a lot of drama and conflict to a fanfiction.
The starters like Chikorita, Cyndaquil, and Totodile are often featured. You could write a story from the perspective of one of these starters as it grows and evolves with its trainer. And let's not forget the Gym Leaders. They are well - known and can add a lot of action and conflict to a fanfiction. For example, Falkner, the Violet City Gym Leader, could be a rival or an ally in a story set in the pokemon silver and blue universe.