The Ethereal serpent is a golden Asian dragon, the first of its kind to appear in the series. Lacking the gracious wisdom of real life Lung and Ryu, there isn't much to distinguish it from its European styled contemporaries aside from its slender body and perpetual levitation. In other words, keep looking if you expect your wish to be granted.
The Ethereal serpent, translated in GBC releases as SkyDragon, is a teleportal boss enemy of the Dragon family at the bottom of the Gate of Wisdom. The ethereal serpent's boss floor design is a reference to the Tower of Transcendence and the Fifer's Spire, two dungeons in the Dragon Quest III that utilize tight-rope puzzles like the later Gate of Wisdom. Of note, the first location where ethereal serpents can fought in that game is at the Tower of Transcendence. Ethereal serpents can be synthesized by breeding a member of the Dragon family with a Firebird. Of note, the ethereal serpent is necessary for synthesizing it's more powerful color variant, Xenlon.
As a remake of the original Monsters game, the Ethereal serpent plays the same role in this title it did on the Game Boy Color – as the boss of the Gate of Wisdom.