When I saw the name Beatrix I thought of the Great and Powerful Trixie, so here's what I went with:
Colors from the pony (and her magic), with circuit because she's lightning.
Cornflower iridescent/Sky striation/ Cottoncandy circuit
For Grommick Reedwing (wind), I went with this:
I like using stained in dull colors to suggest age.
Aqua falcon/Turquoise peregrine/Dirt stained
For Arwin Petalhide (nature):
With a name like that, she's a shoo-in to have petal as her primary.
Cerise petals/Grape butterfly/Rose scales
For Smark Crystalon (Arcane):
I've always thought of this as being a very arcane gene combination.
Navy crystal/Orchid facet/Ice runes
For Caryan Spinehearth (plague)
White ghost over a dark or sickly-looking poitox seems to fit.
Terracotta poison/Spruce toxin/White ghost
For Rish Sunspark (light)
The striped combination of savannah/safari/thylacine reminds me of sunbeams and lasers.
Marigold savannah/Tan safari/Grapefruit thylacine
For Daria Blotburrow (shadow):
I like the idea of camouflage patterns for shadow. I like the way wine okapi covers some of the lighter areas from jaguar.
Clay jaguar/Shadow rosette/Wine okapi
For Rancollo Lavala (fire):
I like the way capsule works as a stand-in for lava on this guy.
Umber tapir/Carmine striation/Vermillion capsule
For Abysaell Deeplake (water):
Jupiter/Saturn/Smoke just screams water to me with its flowy patterns.
Azure Jupiter/Abyss Saturn/Ultramarine smoke
For Galford Rockbreaker (earth):
I like the pebbled texture from spec/frec and the rocky opal adds some nice hard edges.
Forest speckle/Murk freckle/Chartreuse opal
Last but not least, for Amara Frostkeen:
Ice, ice baby! (With some darker stuff like the heart of a glacier)
Ice metallic/Ice bee/Cerulean glimmer