Like Moon Wolves, Unicorns can "evolve" to become True Unicorns and Ultimate Unicorns. True Unicorns require two level 65 Unicorns while Ultimate Unicorns require two level 70 True Unicorns. The primary difference is in their appearance, where they will sprout wings and begin to glow. You will need the True and Ultimate Unicorn Alchemy Scrolls from the Item mall to do this, based on their respective kind. Actual Alchemy or High level alchemy is not required for this.