I'm not sure as I don't typically read such fanfictions. But I would assume some common themes could be the exploration of a unique relationship between Ash and the legendary pokemon, perhaps some kind of power dynamic due to the legendary pokemon's abilities.
Well, in general, in fanfictions like 'ash x legendary pokemon' lemon, there might be themes of forbidden love. Since legendary pokemon are often seen as very powerful and special entities in the Pokemon world, the idea of a relationship with Ash could be seen as something that goes against the norms. Also, there could be themes related to the discovery of new emotions and experiences for both Ash and the legendary pokemon involved.
In these types of fanfictions, one common theme could be the transformation of the relationship. At first, it might start as a curious encounter, like Ash meeting a legendary pokemon in an unexpected way. Then, as the story progresses, it could develop into a more complex emotional and physical relationship. However, it's important to note that this is all speculation as I haven't delved deeply into this specific type of fanfiction.
Often, a theme is adventure. The presence of Legendary Pokemon in Ash's world in these fanfictions usually leads to grand adventures. They might journey to hidden places or face off against powerful foes together. Also, there can be a theme of self - discovery for Ash. Interacting with Legendary Pokemon can make Ash realize new aspects of his own capabilities and his role in the Pokemon world. For instance, if he teams up with Lugia, he might learn more about his ability to communicate with and understand Pokemon on a deeper level.
One common theme is the friendship between Ash and the legendary pokemon. Often, they form a special bond that helps Ash in his adventures. Another theme could be the power of the legendary pokemon and how Ash has to learn to handle it. For example, in some fanfictions, Ash might have to control the immense power of a legendary like Mewtwo without getting overwhelmed.
Protection is also a big theme. Often, Ash has to protect the female legendary Pokemon from villains who want to capture or harm it. This shows Ash's heroic side and also the vulnerability of the legendary Pokemon. In some stories, the female legendary Pokemon also protects Ash in return, highlighting the mutual care between them.
I'm not really into that kind of fanfiction. But you can try searching on some fanfiction websites like FanFiction.net or Archive of Our Own. Just be aware that not all 'ash x legendary pokemon' fanfictions are well - written, and also make sure to follow the site's rules.
Common themes include Ash's evolution as a trainer. He might face challenges that force him to adapt and improve his training methods. Adventure is also a big part. Ash could embark on a quest to find a legendary Pokemon or to solve a mystery that plagues a particular region. Additionally, relationships play a role. This could be his bond with his Pokemon or new relationships with other trainers or characters in the Pokemon world.
Articuno, Zapdos, and Moltres are quite common. Their elemental powers and the mystery surrounding them make for great fanfiction material. Ash might encounter them during his travels and have to either help them or face off against them in some way.
One common theme is Ash forming a special bond with a Legendary Pokemon. Maybe he helps the Legendary in a time of need and they become friends. For example, he could save a Mewtwo from some evil organization and then they team up.
One common theme is the growth of Ash's character. Catching a Legendary Pokemon is no easy feat, and it often forces Ash to step out of his comfort zone, face his fears, and become a more mature trainer. For example, in many fanfics, he has to learn new battle strategies and ways to communicate with a Pokemon that is far more powerful and mysterious than his usual team.
Another theme is the power of friendship. The female legendary Pokemon often starts off as a powerful and somewhat aloof being. But through her interactions with Ash, she learns about the value of friendship. They then go on to face powerful enemies together, relying on their friendship to overcome difficulties. This theme is well - loved as it shows how even the most powerful Pokemon can benefit from human friendship.
A common theme is the development of their relationship. It could start as a simple friendship and gradually turn into something more romantic. Also, the power of teamwork when it comes to catching Pokemon or facing challenges is often a theme. In many fanfics, their individual growth as Pokemon trainers while being in each other's company is also explored. This can include Misty becoming more confident in her skills and Ash learning from Misty's knowledge of water - type Pokemon.