Unicorns show related abilities
Buttons - power to levitate things
Gusty - power to blow gusts of wind from her horn
Ribbon- Telepethy
Fizzy- Bubbles
Galaxy - can make her horn glow
Buttons could also move/manipulate items: in one episode she used her magic to undo a sleeping guard's belt to get the keys off it.
I think Galaxy's power was actually intuition (still lame). All the unicorns horns glowed when they used their magic.