The theme of friendship and loyalty is also prominent. Ash's existing pokemon friends play important roles. They might help him in battles against threats to the legendary pokemon, or they could be the ones who initially form a bond with the legendary, paving the way for Ash to catch it. For instance, Pikachu might use its electric attacks to protect a legendary from an enemy, and this act of kindness makes the legendary more receptive to Ash.
One common theme is Ash's self - less heroism. He often puts himself at risk to help the legendary pokemon in trouble. For example, when it comes to rescuing a legendary from a natural disaster or from villains.
Another theme is the idea of destiny. It's like the universe has chosen Ash to be the one to catch these powerful beings. In many fanfictions, there are signs or prophecies that lead to Ash encountering and catching the legendary pokemon.
There are also fanfictions where Ash catches Rayquaza. This could be set during a time when the sky is in chaos due to some dark energy. Rayquaza is drawn to Ash because of his pure heart and determination. Ash, with his usual courage, teams up with his pokemon to assist Rayquaza in restoring balance. As a result, Rayquaza allows Ash to catch it.
Arceus is quite popular. Given that it's considered the creator of the Pokemon universe in the official lore, it often has a significant role in fanfictions. Mewtwo is also very common. Its powerful psychic abilities and complex backstory make it a favorite for fanfic writers to explore. Another popular one is Lugia. With its majestic appearance and its connection to the sea, it's often a central figure in many stories.
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.
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.
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.
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.
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.
I think Salamence would be quite challenging. It's a very powerful and aggressive Pokemon. Ash would need to have a really strong team to weaken it first. Also, its flying ability gives it an advantage in battle, making it hard for Ash to land a final blow for the catch.
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.
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.