Sylveon is a very charming Pokemon. In a harem scenario, it could be the Pokemon that brings harmony to the group with its fairy - type nature. And then there's Lucario. It's strong, intelligent, and has a sense of honor. It could play the role of the protector in the harem, making sure all the other Pokemon are safe while also having a special bond with the trainer.
Seto Kaiba and Gary Oak would make for a fascinating pair in a crossover fanfic. Kaiba's arrogance and Gary's self - assuredness could lead to some intense rivalries. They might compete to see who can be the best in both the Yugioh and Pokemon worlds. Another interesting character would be Serena. Her kind - hearted nature could be a contrast to some of the more intense Yugioh characters. She could form bonds with the Duel Monsters in a different way than the other characters, perhaps using her compassion to calm down some of the more aggressive ones.
I think Lucario would be an interesting addition. It's a very intelligent and powerful Pokemon. It could sense danger and help Ash make better decisions. Also, Squirtle is a fan favorite. Its cute appearance and water - type abilities can add a lot of fun to the story, especially in water - related adventures.
The main character from the game, of course, is a popular choice. Also, Cyrus from Team Galactic is often included as he is such a complex and interesting villain. And Dawn or Lucas, depending on the version, are great to have as they are the typical Pokemon trainers that players can relate to.
Pikachu is always a popular choice. It's so well - known and cute, and imagining it in a transformation scenario, like turning into a human or another Pokemon, can be really interesting. Another popular character would be Charizard. Its cool and powerful look makes for great transformation stories. And of course, Mewtwo. Given its mysterious origin and powerful psychic abilities, a TG story involving Mewtwo could be very engaging.
In Pokemon, Pikachu is always a popular choice. It's the mascot of the franchise and super recognizable. In Digimon, Agumon is really popular. So including them in a fanfic would draw a lot of readers. Also, characters like Ash from Pokemon and Tai from Digimon are well - loved and would be great to have in a crossover fanfic as they could lead the combined adventures.
You could include the Gym Leaders from Pokemon Ruby. They have distinct personalities and battle styles. For example, Wallace, the Sootopolis City Gym Leader. His elegance and powerful Water - type Pokemon make him a great character. Another interesting character could be Steven Stone. He's a strong trainer and a bit of a mystery. And of course, the Team Magma or Team Aqua grunts. They add an element of conflict to the story.
Ash is always a popular choice. His long - standing relationship with his Pokemon makes him a great character for this kind of fanfic. Also, Pikachu, as it's one of the most well - known Pokemon.
Definitely Ash and his Pikachu. They are iconic in the Pokemon world and having them in a 'pokemon xy' fanfic can add a sense of familiarity and excitement. Serena is also a popular choice as she has her own charm and goals in the 'xy' series. Another character could be Clemont, with his inventions adding an interesting technological aspect to the story.
Pikachu is often used. Since Pikachu is one of the most well - known and beloved Pokemon, it's a natural choice. In reverse harem scenarios, a Pikachu might be very protective of the female character and show its affection in cute ways like cuddling or bringing her berries.
Charizard would also be great. It's a large, dragon - like Pokemon that could fit well into the Star Wars aesthetic. It could be a wild Pokemon that a group of rebels or stormtroopers encounter on an unexplored planet. It could either befriend them or become a formidable enemy depending on how they interact with it.