Old Type Zero
This monster is a small improvement over the Type I, although they are much more uncommon and can only be found in the Clouds Wharf and Conductor Activator, and even then, only if these areas are accessed prior to the start of Phase 5, so Cloche Route players will only see them as partner monsters for some IPDs.
They aren't anything special when it comes to stats, but their skills make them more dangerous than the Type I: they can use Z-STAB, which hits a party member once and causes Pain, thus increasing the damage from subsequent attacks; P-ARMOR, which reduces all damage dealt to them; and finally, S-KILLER, which is a decently fast one-hit slash that has a chance of instantly killing the character it hits. Therefore, the player should be very careful against them and try to eliminate these monsters quickly, as otherwise they might have to revive the characters that get downed by S-KILLER.