One appropriate theme could be Ash's journey to become a Pokémon Master. This can include his battles against different Gym Leaders, his strategies to overcome tough opponents, and the growth of his Pokémon team. For example, a fanfiction could focus on how he trains his Pikachu to master a new powerful move.
Friendship among Pokémon and between Pokémon and humans is also a great theme. A fanfiction could tell the story of how a lonely Pokémon finds a friend in Ash's team or how a Pokémon helps a human in a small village by using its unique abilities. This kind of theme promotes positive values like loyalty, kindness, and cooperation which are in line with the spirit of Pokémon.
One great topic is Pokémon trainer's journey. For example, a young trainer starting from a small town, facing challenges in different gyms, and gradually growing stronger. It can include how they catch new Pokémon, train them, and form deep bonds with their Pokémon team.
Some fanfictions focus on Misty's interaction with other characters in the Pokémon world, not just Ash. For example, her encounters with Brock, or her meetings with other gym leaders. These interactions can lead to interesting storylines, such as team - ups for battles or exchanges of Pokémon - training tips. There are also fanfictions that explore Misty's dreams and aspirations within the Pokémon universe, which can be really inspiring.
One popular theme is the journey of a new trainer. It's about a young trainer starting their adventure, catching their first Pokémon, and learning how to battle. For example, a story could be about a trainer from a small town who dreams of becoming a Pokémon master and has to overcome various challenges in different regions.
One common theme is the exploration of the Johto region. Since Gold and Crystal are set in Johto, many fanfictions focus on the unique Pokémon, locations, and challenges there. For example, the journey through the Ilex Forest or facing the Gym Leaders in Mahogany Town.
Adventure themes are great. For example, a fanfic about a trainer and their Pokémon going on an epic journey to discover a new and mysterious region filled with rare Pokémon. They could face challenges like difficult terrains and powerful wild Pokémon, and along the way, they make new friends and learn important lessons about perseverance and friendship.
Fanfiction about Killua's friendship with Gon and how it evolves over time is also very appropriate. We could see them face new challenges together, and how their bond deepens or is tested in different situations. It would be a heartwarming and positive way to explore the characters.
Another great theme is exploring the backstories of minor characters. Like delving deeper into the story of Rock Lee's childhood and how his determination to become a great ninja in spite of not having natural ninja abilities was formed. It could show his early struggles and the people who inspired him along the way.
A theme centered around the exploration of different ninja techniques within the Naruto universe is also suitable. Writers could imagine new jutsus that characters discover or how they combine existing techniques in innovative ways. This can add new dimensions to the action - packed world of Naruto without delving into inappropriate content.
One appropriate theme could be Naruto's further adventures after becoming Hokage. It could explore how he manages the village, deals with new threats, and continues to uphold the values of the Leaf Village.
One appropriate theme is the growth of the characters. For example, writing about how Naruto further develops his ninja skills and becomes an even greater Hokage. This can explore his training, the challenges he faces, and how he overcomes them.