I couldn't finish 'em. Looks like this's gonna get complicated.
Dark Elemental is an enemy in the Advance and succeeding versions of Final Fantasy V. It can only be found in the Sealed Temple, a bonus dungeon that is unlocked after beating the game. There are four versions of the Dark Elemental, three enemy encounters with different elemental weakness, and a fourth type that appear twice in the boss battle with Grand Aevis.
The regular Dark Elemental enemies have different elemental attributes, split between Fire, Ice, and Lightning. Each is able to cast the highest level of the elemental spells. It can also use White Wind to heal its allies. However, note that the Dark Elemental is weak against the element that it carries; a Dark Elemental that casts Firaga is weak to Fire, and so on.
The two Dark Elementals that accompany the Grand Aevis are of the Wind element. The same attribute on regular enemies applies to the Dark Elementals here; while they can cast the two Blue Magic spells White Wind and Aeroga, they are weak against Wind. It is best to kill them off first before the Grand Aevis as they are annoying healers, however they will respawn when the Grand Aevis is hit.