The Dark Protoss realize the need for heavy support, while the Protoss believed the Reaver worked well enough the Dark Protoss find the Reaver to be slow and only useful in drops. So they took the exo-skeleton of a Dragoon and modified it to create the Marauder. They equipped the Marauder with a Psionic Shockwave Cannon they developed from examining the Terran's Seige Tank. The Psionic Shockwave allows the weaker (then most Protoss or Dark Protoss units)Marauder to stay behind in the attack group and wreak havoc. The Shockwave's ability to attack air makes Marauder's excellent air defense for outlying Dark Protoss colonies.
The Dark Protoss value intelligence even more so then brute strength. By training normal High Templar the ways of the Dark Protoss they created the Intrepid warrior. A Templar that is permanently cloaked, can use the skills the archaic caste of High Templars once knew and the ability to infiltrate enemy encampments and leave behind tracers so they can continually watch the enemy. The Intrepid need only strike an enemy with his Sage Knife to leave behind a tracer. The Intrepid is feared by enemies because they are often never detected and always complete their mission. The ability to morph into a Archaic Warrior or use valuable High Templar skills in a crisis allow the Intrepid to be useful in any circumstances.
The Heavy Viator is the staple air superiorty fighter/bomber of the Dark Protoss. It's the only unit in the StarCraft world made with an even more refined form of minerals giving it incredibly strength and agility, however it also drives the cost up. Its main armaments, the Neutron Cannon and Plasma Bombs allow it to be equally effective at leveling ground forces as well as taking air units out of the sky.
The TerrastaR Missile Frigate is a monstrous unit that strikes fear even in the most hardened battle veterans. Its awesome Impact Warheads have tremendous range and power, but because of this the TerrastaR's hull is less armored and it only carries a small shield generator and it cannot cloak on its own. The large Impact Warheads take up so much space the TerrastaR takes up 6 Psi.
The Dark Protoss are always looking for ways to keep their warriors out of the front lines. This small robotic fighter (based on the Protoss Interceptor) is one of the fastest ships in the galaxy and it boasts a self replenishing Plasma Coil, allowing it to use the devastating Flash Bomb, which was originally designed for the Heavy Viator. Sensing these craft would make excellent escorts for the TerrastaR class Missile Frigate the Dark Protoss removed any thoughts of giving the Evantar a cloak generator and gave it stolen Protoss technology that allowed the Arbiter to cloak nearby units. Because of this the Evantar is pricey for its actual comabt worth.
The Dark Protoss have never had large amounts of resources like the Protoss so when they build a Capitol Ship, they make it huge. The Cruiser is just that ship. It uses a massive 12 Psi, but carriers actual fighters, not drones like the Carrier's Interceptors. The Light Viator Fighters are miniature versions of the Heavy Viator, except they have a Plasma powered Psi Laser instead of a fully powered Laser Battery.