One of the issues with FF7 is that elemental and status vulnerabilities aren't used regularly or consistently, nor are enemies powerful enough for them to be significant. This is a stark contrast to the bestiary of, say, Final Fantasy X, where monster individualization was really well-emphasized. And this is something I want REBIRTH to address.
How so? The simplest method is to use an unofficial enemy class system. These classes might be differentiated as follows:
HUMANS - self explanatory
ROBOTS - androids, automated machinery
PLANTS - plant-monsters, fungal monsters, etc.
INSECTS - bug-like and spiderkin creatures
FLYING - winged beasts
WYRMS - serpents, scaly reptiles, dragons
ABOMINATIONS - things from Hojo's fridge
BEASTS - mamallian creatures
Enemies will take one or two classes, and may take elemental vulnerabilities as follows:
HUMANS - POISON, HOLY
ROBOTS - THUNDER, WATER
PLANTS - FIRE, EARTH
INSECTS - FIRE, WIND
FLYING - WIND, BOLT
WYRMS - ICE, WATER
ABOMINATIONS - HOLY, EARTH
BEASTS - POISON, ICE
The idea is that emental statuses will be simple, memorable and intuitive. As such, if an intuitive elemental defence or vulnerability goes at odds with the official class characterization, the 'commonsense' element classification 'wins'. The above are pretty provisionary, and are still subject to alteration.
Likewise, status effects could work as follows:
Small - works on invertibrates and those without strong internal structures [bugs, abominations, plants]
Confusion - works on those with simple minds [birds, beasts, bugs]
Berserk - works on those with aggressive inclinations [wyrms, bugs, abominations]
Stop - works on the relatively immobile [robots, plants]
Slow - works on the heavy [robots, some wyrms, huge plants]
Silence - works on those that can speak [humans, wyrms (intelligent dragons and serpents)]
Sleep - works on those that *can* sleep [humans, wyrms, beasts, birds]
Dark - works on the diurnal [birds, plants, beasts]
Petrify - works on those that live in the earth [plants, abominations, bugs]
Paralysis - works on those with complex nervous systems, even non-biological [droids, humans, wyrms]
These are all very provisional. And, in part, it's up to you to tell me what you think. Your feedback could have a real impact on how things turn out, so get typing!