I might as well keep a thread that details random details most people don't know and those that look through the number of threads here may have missed or probably don't want to read (I mean, seriously, I have lots of say). I guess this post can serve as something useful that many don't know this info.
So... let's see:
In the Elementals battle, it is not as known that Rubicante has the Mage attribute.
Yang's Endure/Gird command is powered by Spirit.
Yang's Endure command (FF4 only) can always fail while he's Silenced.
When enemies use beneficial spells on you, they are factored against your magic evade, which is why they don't hit.

The Screamer (FF2US name) monster has two enemy type/race attributes. This is how I found out that the enemy type multiplier doesn't stack.
Most Spirits are weak vs Holy. The Weeper (FF2US name) monster is the only type that is not weak vs Holy.
Scarmaglione (aka Milon Z in FF2US) is weak vs Holy (and Fire and Aerial attacks)... he absorbs Holy in the Elementals battle.
He's the only undead that absorbs Holy in the game. D. Bone (FF2US Name) is the only undead that isn't weak vs Holy AFAIK.
Aerial elemental is treated like the all the other elementals in the damage algo.
This sucks because I found out that Kain's Blizzard Spear did effectively the same damage than Cecil's Icebrand Sword...
which also means Rosa with her lame Ice arrows look worse than they should.
When a target is weak and absorb the same elemental... it implies the following:
1) When magic is cast on the target, the target is healed. Absorb is prioritized in this instance.
2) When a physical matching elemental attack is made on the target, the target will take damage as if it were weak. Elemental weakness is prioritized in this instance.
The Dark Elf is not the best example, but if you had Holy accessible at that point in time, you would see how it would heal this target, while being massively hurt by the Legend Sword (those types of weapons use the Holy element)
Who's dumb idea was it to have Tellah speak in the Dark Elf's battle? He is the first to die in that tri-elemental sequence of attacks.
The only way to make his speech sound legitimate is to cast Reflect/Wall on Tellah. I don't know why he was even scripted to talk normally.