One common theme is maternal love. Ash's mom is always shown to care deeply for him. Another theme is the home - a place Ash returns to and where his mom provides comfort. Also, there's the theme of support, as his mom is often depicted as being his biggest supporter in his pokemon - catching and battling adventures.
In some fanfictions, Ash gets angry. He might be angry at the world, at fate, for taking his mom away. This anger could manifest in different ways, like being more reckless in battles or snapping at his friends when they try to comfort him. But deep down, it's just his way of dealing with the overwhelming pain of losing his mother.
Pikachu is a very likely candidate. It's Ash's most iconic Pokemon and has a deep bond with him. Whenever Ash is in trouble, Pikachu often steps up to protect him.
One good 'pokemon ash and mom fanfiction' is 'A Mother's Pride'. It shows how Ash's mom supports his journey in a really heartwarming way. Another could be 'Ash and Mom: Unseen Bonds' which delves into their relationship through some unique adventures that Ash shares with his mom when he comes back home between his pokemon travels.
In some of these fanfictions, a heartbreaking scene could be when Ash discovers his mom's death. He might come home after a long journey, excited to see her, only to find the house in mourning. The silence and emptiness of the place would hit him hard.
Ash could be a Pokémon trainer with a different starting point in this fanfiction. Born in 1987, by 1997 he might have already made a name for himself in local Pokémon battles. He could have a team of Pokémon that he rescued from difficult situations, like a Charmander that was abandoned by its trainer. His story could revolve around giving these Pokémon a second chance and proving that Pokémon don't need to be 'perfect' to be strong.
The impact of Ash's loss in the fanfiction could extend beyond just himself. His Pokémon might also feel demoralized. However, this could also be an opportunity for them to grow stronger together. Ash could start training more intensively, seek new training methods, or even try to catch new Pokémon to strengthen his team.
For Ash, Pikachu is always a great choice as it's his most loyal and powerful partner. Alongside that, a strong flying type like Charizard could be useful. For Brock, his Onix would be a staple. And perhaps a water - type like Vaporeon could be good for him to balance his team. Since they are teaming up, having a psychic - type like Alakazam could also be beneficial as it can help in battles and also with communication in tricky situations.
Ash could also have Charizard. It's a powerful and well - loved Pokemon of his. It could provide a lot of firepower in battles. For Gray, a Glaceon would be great. Glaceon's ice - type moves could complement Gray's more strategic style. It could freeze opponents and give Gray time to plan his next move.
If we consider the common growth pattern in the Pokemon series, Charmander evolving into Charmeleon could be an early evolution in the fanfiction. Since Charmander has a clear evolution line and Ash has a strong bond with it, it would make sense for it to be one of the first to evolve, perhaps due to a tough battle or a special encounter that accelerates its growth.