Ahsoka could face the challenge of time. If there is a ticking clock situation where the Jedi Order is about to be destroyed very soon, she has to act fast. And she may not have all the resources she needs. She might need to gather allies, information, and power, but there could be limitations. For example, some Jedi secrets might be lost, and she has to figure out things on her own without the full knowledge of the Jedi traditions, which can slow down her efforts to save the Order.
In the fanfiction, Merlin might face the challenge of time. If the assassins are about to strike immediately, he may not have enough time to come up with a complex plan. And he has to ensure Arthur's safety not just from the immediate threat of the assassins, but also from any potential threats that might arise as a result of his rescue methods, like leading Arthur into an area that's actually a trap set by other enemies.
In the fanfiction, another challenge Naruto might face is dealing with any mind - control or brainwashing techniques the enemy may have used on Ino and her squad. If they are turned against Naruto, it becomes a more complicated situation. He not only has to free them from the physical danger but also has to break the mind - control. And if the enemy has allies that keep coming, Naruto will have to fight continuously while also protecting Ino and her squad, which requires a great deal of stamina and strategic thinking.
Communication might be a big problem. The crash could have damaged the communication systems on the ship. So, Ahsoka may struggle to let all the clones know what to do. And if there are different groups of clones scattered in different parts of the ship, coordinating their rescue efforts would be extremely difficult.
One major challenge is the Dementors. They are extremely dangerous and can suck out a person's soul. Harry has to find a way to either avoid them or defeat them. Another challenge could be the security measures in Azkaban. There might be magical locks, guards, and other barriers that he needs to overcome.
One challenge could be the strength of the Kumo ninjas. They are known for being tough. Naruto might have to face some powerful jutsu from them. Another challenge could be the distance. If Kushina is held deep in Kumo territory, it would be hard for Naruto to reach her without being detected.
In some fanfictions, Ahsoka might save the Jedi Order by uncovering a hidden conspiracy within the Senate that was targeting the Jedi. She could use her skills as a former Jedi and her unique perspective outside of the Order to expose the plot and gain support from key figures to prevent the downfall of the Jedi.
Robin may also face internal challenges. For instance, if he's doubting his own abilities or if he's emotionally affected by seeing Starfire in danger. This could cloud his judgment and slow down his reaction time. And if Red X has some sort of new weapon or power that Robin is not aware of, that would be another significant challenge in his mission to save Starfire.
One challenge could be the strength of the enemy. If the enemy is very powerful, it would be difficult for Aang to overcome them alone. Another challenge might be the lack of resources. He may need certain items or help from others to save the Airbenders but not be able to get them easily.
The Pokemon might not be ready to evolve yet in terms of its mental state. It could be afraid of the change or not fully understand the concept of evolution, so Ash has to work on getting it to be more confident and accepting. This could involve special training or bonding experiences.
One challenge could be facing powerful new enemies. In fanfiction, authors often create unique and formidable foes for Naruto. These enemies might have strange powers or abilities that Naruto has never encountered before, forcing him to quickly adapt his fighting style. Another challenge could be the moral dilemmas. He might have to make tough decisions in the chaos of war, like whether to sacrifice a few to save many.