Yes, there are likely to be such fanfictions out there. The Harry Potter and Pokemon universes are both extremely popular, and fans often like to combine different fictional worlds in fanfiction. You can try searching on fanfiction websites like Archive of Our Own or FanFiction.net.
As I mentioned before, Archive of Our Own (AO3) and FanFiction.net are good places to start. Just use the search bar on those sites and type in relevant keywords like 'Harry Potter', 'legendary Pokemon', and 'fanfiction'. There may also be some smaller, more specialized fanfiction communities that might have such stories, but those two are the most well - known and likely to have a wide selection.
One challenge is keeping the integrity of both universes. For instance, the magic in Harry Potter is very different from the powers of Pokemon. So, it's difficult to make sure that when they interact, it doesn't seem forced. Another challenge is the different fan bases. Some die - hard Harry Potter fans might not like the idea of mixing it with Pokemon, and vice versa.
Yes, it might be popular. There are many fans who enjoy crossovers like this. Harry Potter has a huge fan base and so does Pokemon. Combining the two universes, especially with a female version of Harry Potter, can attract a lot of attention as it offers a fresh take on both beloved franchises.
I think it is. Fanfictions often take existing universes and mix them up in new ways. Harry Potter has its own set of rules regarding magic and the wizarding world, while Pokemon has its own system of catching and evolving creatures. Combining these two means creating a whole new set of adventures. For example, imagine Harry and his friends going on a quest to find a rare and powerful Pokemon in the Forbidden Forest. It could lead to all kinds of new storylines that we haven't seen before.
Yes, there are many. In some fanfictions, the sword might have the power to cut through any dark magic. For example, it could be able to destroy Horcruxes more easily than in the original story. It might also have the ability to protect the wielder from the most powerful curses.
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 of the Legendary Pokemon could be Giratina. Despite its somewhat dark and otherworldly nature, Giratina might be intrigued by Ash's light - heartedness and his ability to make friends with all kinds of Pokemon. Dialga and Palkia could also be part of the harem. Dialga, with its control over time, might see Ash as an important factor in the future of the Pokemon world. Palkia, in charge of space, could be interested in how Ash navigates different regions and spaces in his journey. And don't forget about Ho - Oh. Ho - Oh is a symbol of hope and might see Ash as a bringer of hope in the Pokemon world, thus joining his harem.
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.