Alternate Universe Role Playing Group's Sapient Species Guide!

Monster Ponies:

Straws Ponies: Similar to Earth ponies, but made out of straw. These ponies are excellent farmers, and are indestructible, except by fire. They can have a small herd of up to five ponies with them at all times. These companions do not need introductions, as they are only to serve. (You can have a small army, and they do not need to apply for a character form.)

Zombie Ponies - The undead. They rise from the graves at dusk, but will often shamble around randomly. They have occasionally wandered into neighboring towns and have been mistaken for drunks.

Werewolf Ponies - Ponies that turn into wolves under the full moon.

WereZombiePonies - Ponies that turn into zombie wolves under the full moon. Makes for great monthly parties.

Goo Ponies - Ponies that are made up of slime. They are completely indestructible, and vary in colors, transparency, and viscosity. Can be spotted by the trail of mucus they leave behind.

Succubi - Insanely beautiful mares that you will end up in bed with no matter which way your barn door swings. Consumes souls on occasion, but are usually just looking for a good lay.

CyberPonies - Remnants of ancient technology from a long past era, these cyborgs are insanely fast, heavily armed, and their minds hold vast libraries' worth of information. Unfortunately, they only speak Marelantian.

Anthropomorphized - The ones with hands.

Camo Ponies - Regular sized and with a sane mind, these are the closest you can get to a regular pony. If you can see one, that is. They're cursed with invisibility that will only leave a slight haze wherever they go. Some can't deal with it and wear clothes year-round, the more desperate get full-body tattoos.

Mirror Ponies - Ponies that turn into whoever is watching them. Their true self can only be observed by themselves. Don't be surprised when you see completely identical ponies (Up to and including any scars, clothes, jewelry, etc...) talking to one another. One of them is a mirror pony.

Mana Remnants - When a ponies die a quick, violent death (Usually by explosions.) their magic is concentrated enough that a pony-shaped cloud of pure energy remains. This "Energy Cloud" is still occupied by their soul, allowing them to be controlled like their biological body.

Glitch Ponies - Ponies surrounded by dimensional instability. They randomly teleport short distances, with the occasional holycrapwheredidtheygo teleports, regardless of their species. Their speech can stutter, jump around randomly, or speed up/slow down with appropriate pitch changes. They can see the future, past, or neighboring dimensions but not know it themselves. Their appearances can change within the blink of an eye, and some have been known to disappear in the middle of a conversation. Subject P1NK13 P13 is thought to be a variant.

Ghoul Pony - A ghoul pony is, essentially, an undead pony spirit without a body, that manifests near a cemetery where zombies have risen. They retain their intelligence and soul after death, which makes them fairly sociable. Ghoul ponies eat dead plants and tree bark. They also enjoy munching on living plants and fruits, vegetables, as well as other organisms, but they can't ingest them.

Armor Pony - A pony's spirit that becomes bound to an object. An armor pony can come in any shape or form, from armor to weapons, and as far as simple jewelry or utensils. Armor ponies are known as such because of the great heroes of old, whom are said to have wielded armors that granted them an undead spirit for guidance and companionship. Armor ponies can only be destroyed if the object to which they are bound is obliterated. They can actively participate in combat despite their spiritual form, but only magical attacks can harm them. Armor ponies can be rebound to a distinct object via a ritual.

Skeleton Pony - Similar to armor ponies. A skeleton pony's spirit is bound to his own bones. Skeleton ponies cannot leave their bound object. Physical attacks can harm them, but they are harder to destroy, as their spirit is bound to each and every single bone they own. Skeleton pony bodies can be repaired if some of their bones are destroyed. All that is needed is a replacement of the original bone and a ritual to perform the binding.

Wight - A wight is basically a zombie who's soul (or at least part of it) remains attached to the body, meaning they retain a good portion of their personality. The bond between their body and soul is kept together through harvesting other souls either entirely or partially depending on quite a few different variables.

Spider Pones - Spider pones are ponies with eight legs. They have infinite amounts of poison that varies from spider to spider. Some can even hide four of their legs to make them seem normal, which makes them very good liars. They normally have dark pelts with different mane and tail colors. The pones normally live in caves or the forest. Only a few live underground. They are extremely lethal and tend to kill any living being that comes their way, because they never know when they'll find their next meal.

Ender-Pony - These creatures are said to originate from the End Dimension and are the pony equivalent of the Enderman. They share many similarities such as pitch black fur, to the glowing purple eyes, tall/slender figure, and they are severely agitated when looked at. They have the ability to teleport at will and can for some reason rip out chunks of materials in the shape of blocks.

Banshees - Banshees look very much like normal ponies, and act like them to a certain degree. They live in large village-like tribes away from Equestria. A banshee has three visual differences from a normal pony. One: They are rarely born with a horn or wings. Two: Their mane and coats are more often than not on a greyscale color, somewhere between white, grey, and black. And three: banshees cannot have cutie marks. Banshees are born with instinctual knowledge of archery and medicinal techniques; honed for several thousand years and passed on through generations, this knowledge of these two subjects, both instinctual and taught, is quite advanced.

Banshees value loyalty, family, honesty, and though they are hunters and can eat meat, they deeply respect nature. If you show respect to a banshee's values, you will not find a more trustworthy companion... or lover...

Banshees are born with vocal cords consisting of several times the layers of muscles that a normal pony has. They can perfectly imitate just about any voice or noise they hear, and can make it sound like two ponies are speaking at the same time. The banshee 'wail' is a defense mechanism designed to incapacitate through a series of rapidly changing frequencies. It will cause temporary symptoms such as migraines, nausea, loss of inner ear balance, partial loss of hearing, and disorientation.

(Thanks to ISKV for a lot of these awesome ponies!)