Known Dark Riders
Not much is known about the powers of the Dark Riders, but it's highly suspected that their powers consists of darkness and evil hence them being the opposite of the Soul Riders.
When facing Sabine in a deadly race, she uses a power similar but opposite of Alex's Soul Strike to stop the player from escaping with the keystone.
Even though, Elise hasn't been seen in person yet, looking from her dark horse and seeing that it bares a heart symbol. Her powers could be the opposite of Lisa's. Instead of giving life, Elise's power takes it, causing disease and illness.