What happened to selphie wakka and Titus on soras island on Kingdom Hearts

In Kingdom Hearts, Destiny Islands was completely overtaken by Darkness. Though it's possible that Selphie, Wakka, and Tidus may have managed to survive somehow (as Traverse Town is where many people who managed to survive the destruction of their worlds ended up, and many fans claim that one of the nameless people you can talk to in town is Tidus), given that it was never expressly stated ingame that they survived (even after talking to the NPC), they more than likely were taken by Darkness as well, to be restored back to their original states along with Destiny Islands and its residents at the end of the first game.

In Kingdom Hearts II, the three of them are living peacefully on the islands. We only see Selphie (who seems to have grown closer to Kairi), and she remarks that Tidus and Wakka are "busy with their ball game," so we've got canon proof that none of them are really caught up in anything strange, though nobody at that time (sans Kairi, and she can really only remember him halfway) can remember Sora - they just remember Riku. Though they often get overlooked, they were among the people whose memories Namine tampered with during Sora's restoration.