This story is a sequel to Sonic Generations: Friendship is Timeless

Everything seemed to be going so well since the fall of The Last Ancient. Twilight and Starlight's time in Sunset Shimmer's world had granted them what they thought would be the final piece of the puzzle that they needed to reach the world that Equestria had almost joined with due to the disruption of time and space. And then Princess Celestia and Princess Luna announced that they would be stepping down.

In her efforts to restore the Warp Ring in the hopes of seeing Sonic and his friends one last time, Twilight inadvertently provided an easy back door to Equestria, allowing Dr. Eggman's chief enforcer to reach it and eliminate any threats the land may pose to the Eggman Empire. As part of his revenge for foiling his plans in the past, Eggman gave strict orders to drag Twilight and her friends to his world so they might see his glorious reign before he ends them for good. Luck proved to be in their favor, however, as the arrival of two friends who haven't been seen in a long time threw a wrench in the works and allowed them to be found by a band of freedom fighters known as the Resistance, led by more of their old friends from that world.

Now part of the uprising to reclaim the world, the Equestrians are hoping to help their allies, new and old, win their war, but time is not on their side. It is the darkest of times for the world, but their efforts may prove to be for naught against their seemingly unstoppable enemy.

Will their friendship and the smallest amount of courage be enough to turn the tides of war?

This story is a sequel to Sonic Generations: Friendship is Timeless

Totally not a spin-off to "Sonic Generations: Friendship is Timeless"; it is a sequel.

When an old, Ancient enemy resurfaces in the world of the Blue Bomber and his heroic friends, craziness ensues when they try to stop him that ends up sending everyone to a whole other world.

Stranded far from home, Team Sonic must make new allies and attempt to fit in in this new world while also trying to gain the trust of its inhabitants and reclaim the Lost Crystal of Power before their foes do.

Will Team Sonic be able to balance a life of their typical heroics with going to school? Will their new friends be able to show them new powers they'd never imagined were real before? Will Amy finally get her new snakeskin boots? And will Sticks eventually stop messing with the author?

"Don't count on it."

Find out in this, the ultimate crossover of awesomeness!

Set between MLP:FiM Season 3 and 4.

Sonic, Tails, and Knuckles find themselves against Dr. Eggman once again, the scientist wanting to use the Chaos Emeralds for an unknown plan.

Unfortunately, the plan involved sending the trio to another world, which he plans to conquer as well as seek what are known as the Elements of Harmony. The fate of Equestria hangs in the balance as the heroes of both worlds must join forces against Eggman's robot army.

Can Team Sonic and the Elements foil Eggman’s latest scheme or will they fail?

Spin-off story to "Sonic Generations: Friendship is Timeless", taking place between chapters fifteen and sixteen during the train ride to Canterlot.

Everyone knows that Sonic, Tails, Spike, the Main Six, Shining Armor, and Princess Cadance set out for and arrived at Canterlot aboard the Friendship Express to find and stop the monster that had intertwined two worlds and their fates together, but what happened along the way? While Princess Celestia and Princess Luna went on ahead and prepared for their arrival, Equestria and Earth's heroes had to go through more adventures in order to get to Equestria's capital city. Now, the story of their lesser known adventures shall be told.

So climb aboard the Friendship Express, grab a seat, and get comfortable. It's going to be quite a ride.

Sonic Generations: Friendship is Timeless TV Tropes page can be found here.

I've seen this idea done before, but as a fan of Sonic and MLP: FiM, I wanted to give it a go myself.

This, basically, is the story of Sonic Generations, but crossed over with the MLP:FiM universe, with Spike and the Main Six taking the place of Classic Sonic and Classic Tails with other MLP characters also appearing (most aren't listed to prevent spoilers). Except for Green Hill, there will be different areas explored, as well as pony rivals and different era bosses. So while it will have its similarities to the console and 3DS versions of the actual game, it will definitely have its differences too.

Also, in case anyone was wondering, there will NOT be any shipping in this story. At the very least, no crossover shippings. No SonicxRD, TailsxTwilight, TailsxFluttershy, or anything like that. If there is any shipping at all, it will only be between characters from the same universe. And the only humans in this story are Dr. Eggman and the ones that appear in the "Sonic Unleashed" level.

A big thanks goes to bvge on Deviantart for creating the new logo on the cover art. It's a vast improvement over the old cover art.

The TV Tropes page can be found here.

NOTE: Due to the length of many of the chapters in this story, most of them have been broken up into smaller parts of roughly 10,000 words or less to make the story easier to read.