Who might be responsible for Ash getting caught in a pokeball in the fanfiction?

Well, it could be that Ash gets caught in the Pokeball by accident. Once inside, he might start to understand the feelings of Pokemon when they are captured more deeply. He could try to figure out a way to escape, and in the process, learn some secrets about how Pokeballs work that he never knew before.

It could be a Sith or a Sith - inspired enemy. They are often the ones causing trouble for the Jedi, and shooting Ahsoka would be a way to strike at the Jedi Order.

There's also a possibility that it's an accident. In the chaos of a battle or a tense situation, a stray bullet from either side could hit Katniss, even if no one actually intended to harm her directly.

As I mentioned before, a member of his own wolf pack. In a pack, there can be jealousy and power struggles. If another wolf wants more influence or has a grudge against Jacob, they might be the ones to cause him harm.

It could be an enemy that manages to sneak onto the Argo 2. Maybe a monster that they thought they had defeated before but actually just bided its time and then attacked Percy when he was least expecting it.

It could also be an ancient prophecy that is misinterpreted. The Oracle might give a prophecy that the gods misunderstand as Percy being a threat. So, in an effort to prevent the prophecy from coming true in what they think is the wrong way, they disown him.

There's a possibility that it's an old enemy who has somehow regained power or found a new way to attack. For example, Frieza's family or the Red Ribbon Army if they had some kind of resurgence. They might target Vegeta and Bulma out of revenge or to gain access to Capsule Corp's technology which Bulma controls.

A new and powerful rogue ninja could be responsible. This ninja might have a vendetta against Konoha and see Naruto as a symbol of the village, so they target him and use their strong and devious techniques to injure him badly.

Another possibility is a jealous student at Hogwarts. There are always students who might be envious of Hermione's academic achievements. They could set up a prank or a trap that goes wrong and ends up hurting her. For example, a student who is tired of Hermione always getting the top grades in Potions might tamper with her cauldron during a class experiment, resulting in an explosion that hurts her.

In a fanfiction scenario, Ash might be in a situation where he has to use a unique Pokeball to catch Lugia. The Pokeball could have some sort of special power, like being able to withstand Lugia's powerful attacks. Ash would have to figure out how to use this Pokeball effectively while also respecting Lugia's might and the bond that Lugia has with the sea.