It shouldn't have been a big deal. Celestia was kidnapped or knocked out or just generally made to seem powerless by whatever idiot with ill intent decided to show up on a nearly weekly basis. As the mighty and immortal Sun Princess, she could escape at any time, but she was happy to play these little games. The daring rescues and bloodless battles gave her ponies such a sense of confidence and purpose!
But this one didn't go as planned. One small, stupid mistake got her thrown to the twisted reaches of the world-prison, Tartarus. Now alone, unarmed, and barely more than mortal, Celestia wakes in a living landscape where everything has every reason to hate her.
And, far worse, she has accidentally picked up a passenger.

Sidenote: This a repost (I tried to go through official channels, I promise!) of a story I wrote long, long ago on an account I foolishly deleted. Back in those days, Tartarus hadn't shown up in an actual episode yet. It's not exactly an alternate universe situation, but it has nothing to do with the canon portrayal of the place.

Super amazing cover art by Cold In Gardez.

Some people say that Celestia and Luna are useless. That they lounge in the castle while delegating all their responsibilities to hard working, underappreciated, exceptionally well-read students. That even when faced directly with threats to kingdom and country, they fold like cheap origami and wait to be rescued.

These people are correct. But there's a very good reason for it!

[Rated Teen due to a dark scene early on to set some backstory, and occasional comedic death]

A machine made for war awakes in a new world. Stuck in surroundings which puzzle it; can it, or will it be able to become something more than what it is?

Crossover with Keith Laumers Bolo-verse
Other tags include : Slice of Life, Possible Romance believe it or not! And a bit of humor.
Please beware of any spoilers in comments as well

Please do check out the Reading List by Lance Omikron to navigate the Amalgam Universe most clearly

A massive war of titanic forces is taking place in the Kaiju's world. However, when two faction's leaders, the current Godzilla and his 'brother' Xenilla duke it out; humanity unleashes its most devastating weapon. Something beyond comprehension occurred and the boundary that divides worlds, if only for the briefest of moments, was torn to shreds. New forms are taken, new bodies assumed. But old hatreds die hard. But how well can hatreds continue in the world of love and tolerance? Especially with its own demons follow it there?

Godzilla Franchise by Toho Company Ltd.
My Little Pony is owned by Hasbro Studios.
This is a non profit fan-work and I claim no ownership on the IP itself.
Story created by Tarbtano
Co-created and Contributed by Faith-Wolff and Skylark8756

HOLY SHEETZU WE GOT FEATURED! THANKS GUYS!
6/27/2014
Now on TV tropes (Thanks Raidrik, VampyGirl; Lance Omikron, Ultimomant, and ZimFan!)

Kaiju Cast:

Godzilla a.k.a Gojira
Xenilla
Mothra
Anguirus
Rodan
Destroyah

[Character copyright of Toho and Daiei Company, artwork property of Matt Frank]

(for any G-fans, Xenilla is the kaiju you may know as Spacegodzilla. I changed the name because I got quirked about typing it repeatedly and am writing the story so it can at least be understood by just an MLP or just a G-fan; and thought it get very confusing that one character's name was just another character's name with an adjective. Also... don't pretend it's the most imaginative name Toho has every made)

All of Equestria is united in celebration for the return of their beloved Princess Nightmare Moon. But when Celestia and everypony else recieve her she's skeletally starved, filthy, and very nearly dead. Meanwhile, while everypony's eye is turned, a lusty Blueblood pursues Twilight Sparkle, intent on adding her bloodline to his own so his family might step closer to godhood. (Alternate Universe, there never was a Princess Luna)

Warning: Silliness inbound.

By order of the high lords of Terra themselves, a lone soldier from the Death Korps of Krieg has been sent to the planet Epona to wipe out its Xeno population. Starting with Equestria, the Korpsman has sworn not to leave the planet until he falls or completes his mission.

However, no Korpsman should fight without setting up a proper trench first, and so the Korpsman must dig...and dig...and dig.

Destroying Equestria is going to take a while.

Sunset Shimmer has recently been reformed from her disaster during the Fall Formal. In her desire to direct her ambition for something worthwhile, she wants to learn an instrument.

Well....She heard one guitar....

Coverart

(Warning: contains a lot of classic rock)