There are many ways fanfiction writers can take this concept. They could write about the baby having special powers or a unique connection to Pokemon. It could also be a story about the family traveling together, with Ash and Serena passing on their knowledge and values to their child. This type of fanfiction can be a great exploration of family dynamics within the Pokemon universe.
One aspect could be the naming of the baby. Since they live in the Pokemon world, the name might have some connection to a Pokemon or a special place they've visited. Also, the story could involve the baby's first encounter with a Pokemon, which could be a really cute and heartwarming moment.
Their Pokémon would probably be very protective. Pikachu, being Ash's closest companion, would always be on guard around the baby. It might even try to play with the baby in its own cute way, like using its electric shocks to create little light shows to amuse the baby. Serena's Pokémon, like Fennekin which evolved into Delphox, could use its psychic powers to sense if the baby is in any danger or discomfort. All of their Pokémon would likely adapt their usual habitats and behaviors to be more baby - friendly, for example, making sure not to use any dangerous moves near the baby.
The story could start with the discovery of Serena being pregnant. Ash would be overjoyed but also a bit nervous. They might go on a journey to find a special place to raise their baby, perhaps a place with a unique Pokémon environment. Along the way, they meet old friends who offer advice and support. When the baby is born, it could inherit some of Ash's determination and Serena's grace. And as the baby grows, they start to train it to become a great Pokémon trainer in its own right, passing on their knowledge and values.
Well, the plot could be about their journey into parenthood. Maybe they start off by being a bit nervous but then gradually learn how to take care of their baby. They could face challenges like the baby getting sick or having trouble sleeping, but they rely on their love for each other and the baby to get through it all.
Their relationship would become more mature. They would have to rely on each other more than ever. With a baby, they'd have to share responsibilities, which could lead to a deeper understanding and respect for each other.
Maybe in the fanfiction, they go on a special journey together. During this journey, they face a unique Pokémon that has the power to bring out hidden emotions. This makes them realize their love for one another. As a result, May gets pregnant. Ash is super excited and a bit nervous at the same time. They then start preparing for the baby, like building a nursery in a peaceful Pokémon - filled area where they plan to raise their child.
One possible storyline could be that Ash and Serena settle down in a peaceful region, perhaps near a forest. They start their family life and the baby could inherit Ash's love for Pokémon battles and Serena's grace. The baby might grow up surrounded by Pokémon, learning about different types and their behaviors from a very young age.
The plot could involve Ash and Serena finding a baby Pokémon that is in a situation similar to being an orphan. Since they have such a strong bond, they decide to take it in and raise it as their own. They then have to learn how to take care of this special Pokémon baby, which includes finding the right food, a safe place to live, and teaching it important skills. Their friends from their Pokémon adventures might also get involved, some being supportive and others being a bit skeptical at first.
One idea could be that their baby has a special Pokemon - like a Pikachu that was born with a unique marking. It could start to show amazing abilities from a young age, and Ash and Serena have to figure out how to help their baby train it.