One idea could be that Ash has to quickly grow up and take on more responsibilities to support his mother during her pregnancy. He could start doing odd jobs around town to earn money for things like baby supplies.
Another plot could be that there are some complications during Delia's pregnancy. Ash becomes determined to find a way to help, so he sets off on a journey to find a rare Pokémon or a special herb that is said to have healing properties. Along the way, he meets new people and Pokémon who teach him valuable lessons about life and family.
Perhaps Delia's pregnancy makes Ash realize how much he wants a family of his own in the future. He might start to look at his relationships, like with his Pokémon, in a new light, seeing them as a sort of family unit. And he could also start learning about parenting from his friends' parents.
Another plot could involve a situation where a powerful Pokemon is attracted to Ash's kind heart, but Delia's possessiveness makes the Pokemon sense some sort of danger or instability in Ash's life. So, it tries to test Delia to see if she can let go a bit for Ash's sake. This could lead to a series of adventures where Ash has to balance his mother's feelings and his own Pokemon journey.
One idea could be focusing on how Ash's friends react to the news. They might be shocked at first but then rally around to support her. Another could be Ash dealing with the physical and emotional changes during pregnancy while still trying to pursue her goals.
One idea could be that they discover the pregnancy during their travels and have to figure out how to balance their adventures with the upcoming baby. For example, they might need to find a safe place to stay for a while.
One plot idea could be that they go on an adventure together while May is pregnant and face some challenges related to protecting the unborn child. For example, they might encounter some wild Pokémon that are unusually aggressive, and Ash has to use his skills to keep May and the baby safe.
One interesting plot idea could be that Delia, Ash's mother, has some long - lost connection to Giovanni. Maybe they were childhood friends before Giovanni took the path of the villain. Another could be a story where Giovanni, for some reason, has to protect Delia from other evil forces in the Pokemon world, which turns into an unexpected alliance. And a third idea might be that Delia discovers a secret about Giovanni's past that makes her question her own understanding of good and evil in the Pokemon universe.
One plot idea could be that Ash and Serena discover they're pregnant during their journey. They then have to decide whether to continue traveling or find a safe place to settle for a while. Another could be that they face challenges from Pokémon battles while Serena is pregnant, and Ash has to be extra cautious to protect her and their unborn child.
One plot idea could be that they embark on a journey to find a special place to raise their child. They might face challenges along the way, like dealing with wild Pokémon that are more aggressive due to the new energy they sense. Another could be that they start a Pokémon training school for their unborn child and other kids in the region, teaching them about Pokémon care and battle strategies.
Another plot could involve the reactions of their friends. Pikachu might be really curious and try to help in his own little way. And the other Pokémon friends could also offer their support in different ways, like gathering special berries that are good for Latias during pregnancy.
Ash could become more empathetic. His mother's pregnancy would expose him to new emotions and situations. For example, he might notice how difficult it is for Delia to move around or do simple tasks, which would make him more sensitive to others' struggles.
One idea could be that they reunite after a long time apart. Ash has become a more mature trainer and Serena has achieved her dreams too. They realize their feelings for each other have deepened. One passionate encounter leads to Serena getting pregnant. Then they have to deal with how their families and friends will react, and also how they will balance their future goals with raising a child.