Well, Sasuke's abilities would be quite interesting in the Attack on Titan world. His teleportation - like abilities, like when he uses his Susanoo, could help him quickly reach the nape of a Titan's neck for a kill. And his chakra control would allow him to enhance his physical abilities even more. He could jump higher and run faster, which is crucial when dealing with Titans. Moreover, his intelligence and strategic thinking from his experiences in the Naruto universe would make him a valuable asset in the fight against the Titans. He could come up with new tactics to deal with different types of Titans.
Sasuke's sharingan would give him a huge advantage. He could predict the movements of the Titans, much like he does with his opponents in the Naruto world. His ninjutsu skills, such as fire - style jutsu, could be used to fend off Titans. For example, he could use his fire - style to blind a Titan or create a barrier of fire to keep them at bay. Also, his speed and agility from being a ninja would make him a very effective fighter against the Titans. He could quickly move around the battlefield, avoiding the Titans' attacks and finding their weak points.
Sasuke's presence in an Attack on Titan fanfic would change the dynamics of the fight against Titans a great deal. His ability to use genjutsu could potentially be used to confuse Titans. If he could put a Titan under a genjutsu, he could make it attack other Titans or just stand still. His swordsmanship, which he has honed over the years, would also be useful. He could use his sword to slice through the tough skin of the Titans more effectively than some of the Survey Corps members. Additionally, his Sharingan could help him analyze the Titans' anatomy better, allowing him to find the most efficient way to kill them.