This Fourm is made for those who are unfamiliar with Crisis: Equestria's cast. Keep train mind that may certain parts will be changed over time and they contain spoilers. Go here for the list of Protagonists. The Antagonists of this story are the following:
Nihilia, Goddess of Discord
Lord Silvertongue
Shadowstep
The Mean Six:
Havocwing
Red Velvet
Curaçao
Starlight Shadow
Insipid
Grayscale Force

Silvertongue

The ruler of New Pandemonium. Silvertongue, along with his various associates and loyal minions run the chaotic city with an iron hoof. Cunning, ruthless, efficient, and warden to an all-powerful goddess of darkness, Silvertongue is a force to be reckoned with in the world of Equestria-V.

He does not tolerate inadequacy from his subordinates. His punishments for failure range from being thrown to zombies, to being used as cannon fodder in his experiments. He originally starts off as a servant to the goddess Nihila. But then, after the creation of the Mean Six, he betrays her and absorbs her powers, effectively becoming a god.

Shadowstep

Shadowstep was Silvertongue's master assassin until one day he failed to kill his target: The Chronomancer Tick Tock. Silvertongue punished him by performing a harsh experiment on him that, while painful, gave him special metal wings that are resistant to any magic that isn't Silvertongue's, his wings can cut through any magic barrier like a hot knife through butter.

Silvertongue wasn't done with him yet however, as further punishment for his failure, he tossed him in a zombie-infested wasteland where he was eventually turned into one of them. Despite this, Slivertongue still saw use for him and used his magic to let him keep his mentality unlike any other zombie. As a result, he is now immune to pain and fatigue, making a deadly force to be reckoned with.

Starlight Shadow

The evil clone of Twilight Sparkle, she represent's the Element of Discord and the uncontested leader of the Elements of Discord, to the point that the other call her “Boss” rather than by her name. Oddly enough, she's the youngest of the six.

She specializes in "Anti-Magic", a power that stems from "Void magic". This gives her incredible magical power that only Twilight Sparkle can equally match in strength. Despite this, she considers herself superior to Twilight in every possible way.

She is very arrogant and is not above calling herself "a goddess among mares", this is mainly due to the fact that she possesses enough power to tear through mountains, rip apart metal gates weighing several tons, mass-teleport incredible distances, and has a barrier spell powerful enough to withstand the might of a goddess.She is in no way shy about letting everypony know just how powerful she is.

Havocwing

The evil clone of Fluttershy, she represent's the Element of Fury. Although she has a VERY short temper and get pissed off at just about anything and everything. Due to being the second oldest sibling, apparently very protective of her sisters, when she's not threatening to murder them herself of course.

Havocwing is capable of manipulating fire. She can shoot fireballs, trail it behind her as a solid wall of flame, generate a jet with it to increase her speed, and empower herself with it to become a living ball of fire.She seems to have inherited some of Fluttershy's memories of Iron Will, and presents her "Assertiveness Advice" to Fluttershy in rhyme. She is apparently decidedly better than him. As the rhymes Havocwing comes up with are off the top of her head to match the situation:
"If somepony says you're scared of the dark, show them your bite's worse than your bark!", "Somepony jerking you around? BETTER BURN THEM TO THE GROUND!"

Red Velvet:

The evil clone of Pinkie Pie, representing the Element of Fear. She's basically the Pinkie Pie from Cupcakes taken Up to Eleven. Her primary power is her ability to manipulate her blood as a weapon, usually in the form of blades or tentacles. Her other power is her ability to inspire and feed off of the fears of others, and to worm her way down into the psyche of anypony and find out what they fear the most. Another manifestation of Velvet's bloodbending is her ability to recover from wounds extremely easily, hence why she has little fear of pain except when inflicted in such a way that she can't heal it.

Velvet loves to dish out the pain, and doesn't at all seem to mind getting hurt in combat whatsoever, she appreciates an opponent that can actually hurt her. Velvet does not like being laughed at, and despises any definitions of "joy" and "happiness". Her biggest quirk is her habit of taking nursery rhymes and children's songs, as well as Pinkie Pie's own original tunes, and turning them into insidious promises of doom. Her crowning moment is "Scream", her epic reprise of "Smile", during which she completely defeats Applejack, Flathoof, Pinkie Pie, and Ophanim all at the same time:
"Come on everypony, scream, scream, scream! Let your hearts fill with nightmares, nightmares!"

Grayscale Force:

The evil clone of Rainbow Dash, representing the Element of Apathy. She is extremely intelligent, but lacks motivation to use her intellect for anything more than how to end fights quickly so she can get back to her napping. However, when given the proper motivation by providing a fair challenge to her, she becomes an incredibly threatening individual.

Grayscale's powers give her a control over the gravity of objects within a certain field of space. Her wings are required to manipulate the gravity in other objects, making it difficult for her to fly and use her powers at the same time. She can manipulate her own weight freely however. She later shown to be a supremely logical fighter and speaker who cares more about results than about methods.

Insipid:

The evil clone of Rarity, representing the Element of Avarice. Her power allows her to copy the powers of other ponies by merely touching them. However she is unbelievably dumb, from not knowing how powers she steals work, to not knowing the proper pronunciation or definition of words, to most especially not remembering the names of anypony except her sisters and Rarity, her original. Insipid is singularly obsessed with her sister Curaçao, seeing her as the object of her devotion and adoration. She tends to talk like a stereotypical Valley Girl,like, all the time.

Curaçao:

The evil clone of Applejack, representing the Element of Deceit. She is the oldest of the six. She has the ability to change her coat to blend into the environment, rendering her totally invisible, or transform her body shape to take that of anypony she wishes (no, she's not a changeling).

When disguised as somepony else, Curaçao is able to play them to a 'T'. Her skill is so perfect that she was able to fool her own sister's into thinking she was Applejack, and didn't break character even when Starlight was threatening to mindwipe her.

Curaçao is also a very good liar, to the point where it's actually hard to tell sometimes if what she's saying is true or not. She can apparently tell if somepony else is lying or telling a half-truth. She always speaks French(or "Romantique" in Equestria). She is bar none the brains of her group, well-versed in the arts of magic and combat to the point that she is almost solely responsible for all of the ambush plans her party has sprung on the heroes, including divvying up the target assignments. Grayscale Force is admitted as being her assistant, but only that - her assistant.