Nickelhorses (spelled both "nickel horse"IPTSF Text 3 and "nickelhorse"IPTSF Text 5) are Mount Units in service to Goodminton - together with Quarterhorses.IPTSF Text 3 Their appearence and abilities are yet unknown.
Real World References
In Goodminton, Wanda observed how "stalwart knights led alternating charges at one another on quarterback, then on nickelback". This may be a reference to quarterback and nickelback - player positions in American football.
Nickelback is a Canadian hard rock band.