AIRBORN ATTACK UNIT
Slice and Dice

This mechanical beast, something between a scorpion, a dragon fly, eight circular saws, is seen chasing down the run away train in the trailers. This is more than likely a boss enemy due to it sheer size and power. The airborne machine successfully stops the train in the trailer and reveals it's enormous circular saw-esk arms as it faces off with Lightning.

BEHEMOTH
Might be, Tough to Call

This heavy steroid abuser is thought largely to be the Behemoth of Final Fantasy XIII, or at least a note worthy variety. This particular one here has quite the intricate head dress, complete with large colourful ribbons, a lot of metal and some decorative leather that falls on the sides of it's face. Besides noticing the dead look in it's eyes, big teeth and more razor sharp claws, this Behemoth also comes with pants. Yes, pants, and sleeves as well, perhaps belonging once to a shirt.

The metal head dress seems to also act as a weapon, flipping forward with the flick of the extremely muscular neck. Behemoth's fighting style alone shows that this creature is obviously intelligent as it has no problem running around on all fours, or standing up to swing it's enormous sword which even puts the Buster Sword to incredible shame. Behemoth appears in the Final Fantasy XIII trailer when it seems to be summoned from within traffic on a busy highway.

DRONEGUARD
The Rolly-Polly in the Back

These drone guards are only seen for a moment in the trailers, but from what is seen, they seem to bob around smoothly. They look to be large rolly-polly-esk police robots, which would help explain why they're seen side by side with other law enforcement, as well as explaining the large flashing red police light on the very top of them.

No forms of offensive equipment has been seen with these robots. They may very well be beverage dispensers, intimidation robots (they don't look too sinister, but they have a sharp glare for how bobby they really are), or possibly decoys or mobile storage for arms and ammunition.

SOLDIER
Expect Lots of Them

Highly trained killing machines in theory, incredibly weak enemies in reality. The soldiers from the trailers are probably not from the beginning of the game. In but a single attack, Lighting casts Fire, and hits a group of soldiers, dealing roughly 800-1200 HP in damage. This is more than likely quite a few hours into the game considering the player can do that amount of damage.

BLUE SOLDIER
The scout, perhaps?

These blue coloured soldiers look rather similar to the regular yellow soldiers we've seen thus far, excluding the uniform color. It's hard to judge the difference between this soldier and the others, but he might be a Scout as one attacks Lightning with a short energy rod, which looks to be quite the underpowered weapon. They also look quite agile, but low on armor, the usual correlation.

ROBOT
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As Lightning is in the middle of dancing with Guns and Swords, these stubby-limbed robots are seen falling out of the sky from drop ships. It's a good thing they've got rocket propulsion built into their leg-like torso stubs...

These robots have quite a large collar and what looks to be six eyes, folding arms, a Samus-esque gun arm, four long rods sticking out of their back and a paint job good enough for a formal dinner. They also all seem to come with a rainbow of different weapons from robot to robot, from the gun arm, to an arm with six foot longer spikes, and also a shield.

BEAST
Rawr!

A cybernetic K-9 or large cat of some sort, similar to the K-9-like Deepground beasts from Final Fantasy VII: Dirge of Cerberus.

This creature also looks similar to large wild cats, like a leopard or tiger, just without the fur, ears, eyes, and 2 digits off each paw. Their skin also looks quite thick, which explains why it likely takes many many bullets to kill them, yup, that explains everything.