You can make it unique by changing the setting. For instance, if Ash starts with a Bulbasaur in a post - apocalyptic world where most Pokemon are scarce. This would force him to find new ways to train and care for his Bulbasaur, and also deal with other survivors who might be jealous or desperate for his Pokemon. It would be a completely different dynamic from the original series.
One idea could be that Ash starts with a Pikachu that has a rare and powerful hidden ability. This could lead to different battle strategies and interactions with other trainers. For example, instead of the usual Pikachu that gradually grows in strength, this one could be super strong from the start, causing other trainers to be both intimidated and curious.
He could have a Froakie. It's a common and cute starter in Kalos. Maybe also a Skiddo for traveling across the Kalos landscapes. And a Bunnelby would be a nice addition for its digging abilities.
One possibility is that Ash's Ekans could be a special one with unique abilities. Maybe it has a hidden power that helps Ash in battles against stronger opponents. For example, it could have a super-effective type of attack that is not common among Ekans, like a special poison - type move that can paralyze opponents for a long time.
If Ash starts with a legendary pokemon such as Rayquaza, it could be that there are abnormal weather patterns in the Pokemon world. Rayquaza has the ability to control the weather. Ash and Rayquaza team up to figure out what is causing these extreme weather changes. Along the way, they meet other trainers who are also affected by the weather problems. Ash has to prove that he is worthy of having a legendary pokemon by using Rayquaza to restore balance to the weather.
Well, one possibility could be that Ash's Ralts has a special ability that sets it apart from other Pokémon. Maybe it can communicate with Ash in a unique way, like through emotions. This could lead to Ash having a deeper understanding of Pokémon in general.
Well, obviously Ash is one of the main characters. He's the protagonist of the Pokémon series and his journey in Alola is the focus. Pikachu is also a main character as Ash's loyal Pokémon partner. In Alola, there could be new friends like his classmates from the Pokémon school, such as Kiawe, Lillie, and Sophocles, who would also play important roles in the fanfiction.
In this fanfiction, Ash could start in a mysterious forest and spot a shiny Celebi. Celebi, being a time - traveling Pokemon, could take Ash on a journey through different time periods in the Pokemon world. He might see how the Pokemon world has evolved over time, meet some of his ancestors or future versions of himself, and have to solve various problems in each time period to keep the balance of the Pokemon world.
Well, one possibility is that Ash meets the shiny ghost pokemon early on his journey. Maybe it's a Gastly that has some special power. Ash could then try to befriend it, facing challenges from other trainers who also want this rare pokemon. The shiny Gastly might lead Ash to an old, haunted place full of secrets about pokemon evolution or some long - lost pokemon techniques.