I had an issue where they immediately desynced when using them online

No clue about the cause, it just happened within like 5 seconds of the game starting

It's the n special that crashes, mainly the after images

Ziinkh has a giant hitbox that covers the entire stage, immediately destroying all projectiles that enter. To see what I mean, open training mode with Ziinkh and Ranno, and then turn on hitbox view. Also, try to use any projectile while in a match against Ziinkh.