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 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.
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.
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.
One idea could be Ash traveling to a new, mysterious region full of never - before - seen Pokémon. He could encounter a powerful and rare Pokémon that becomes his new partner. Another could be Ash getting lost in a time - warp and having to find his way back while also learning about the past of the Pokémon world.
Another plot could be that Ash enters a high - stakes Pokémon tournament in Cynthia's region. Cynthia becomes his mentor, teaching him advanced strategies, and they develop a strong friendship along the way.
One idea could be Ash and Togepi getting lost in a mysterious forest. They encounter strange new Pokémon and have to work together to find their way out. Another plot could be Togepi getting sick and Ash having to search for a rare herb to cure it. He meets different trainers along the way who either help or hinder his quest.