Phantom Navis are phantom copies of NetNavis.
Phantom Navis are phantoms that take on the properties of any NetNavis. It is essentially an exact duplicate of the Navi in question. They include physical appearance, voice, memories, and even chips and moveset. However, it is more evil than their original counterparts and can be distinguished by the multitude of rings in their eyes. Phantom Navis are able to materialize in the real world by sheer will, without explanation. All phantom Navis share one weakness. They will disappear if they are damaged, even slightly.
It is revealed that the Phantom Navis are created by Cache.