This story is a sequel to Doctor Whooves Episode 8: Maiden Voyage

The TARDIS brings the Doctor, Twilight, Derpy, and the others to the Griffin Kingdom in the year 1021. Here they meet a 38-year-old Rainbow Dash training for the Gailenean 1000. Meanwhile, a third Rainbow Dash from an alternate reality appears but with much darker goals in mind.

This story is a sequel to Doctor Whooves Episode 7: The Good, the Bad, and the Derpy

The Doctor, the Mane 6, Derpy, and Spike travel to 4376 and find themselves on a luxury spaceship called the Queen Philippine, which is currently on its maiden voyage. What starts off as an interesting adventure turns into a fight for survival when the ship loses power and becomes host to some unwanted passengers.

This story is a sequel to Doctor Whooves Episode 6: A Ponyville Invasion

With Thalia continuing her invasion of Ponyville, Derpy and the others find their last chance at stopping her in the hooves of a future regeneration of the Doctor. Meanwhile, the Doctor teams up with an ally from the past to rescue Twilight and Rainbow Dash and ultimately save the town.

This story is a sequel to Doctor Whooves Episode 5: Before the Chaos

The Doctor finally manages to return Twilight to 1002, only to discover that he's brought her back a little bit late. As the suspicious citizens of Ponyville turn on the Doctor, a strange army led by an old foe invades the town.

This story is a sequel to Doctor Whooves Episode 4: Young Armor

The Doctor and Twilight have picked up a mysterious mare named Matilda who seems to know them pretty well. While they try to uncover Matilda's secrets, they find themselves in Equestria 100 years prior to the birth of Princess Celestia. Here they come across a kind and caring King Discord and his wife, Lily, who holds the key to his descent into chaos.

This story is a sequel to Doctor Whooves Episode 3: Aliens Among Us

After leaving Eugora, the TARDIS takes a giant leap through time and sends the Doctor and Twilight to Canterlot in the year 987. Here they come across an 8-year-old Shining Armor who is dreaming of becoming a royal knight. However, a devious villain has set her sights on the young unicorn and it's up to the Doctor and Twilight to save his magic, his life, and his future.

This story is a sequel to Doctor Whooves Episode 2: The Awakening

The TARDIS takes the Doctor and Twilight to the planet of Eugora in the year 1899. Here they come across a group of pony soldiers, explorers, and scientists. However, the forests of Eugora hide dark secrets and the Doctor, Twilight, and others find themselves facing off against two deadly enemies, and the Doctor knows one of them.

This story is a sequel to Doctor Whooves Episode 1: The Doctor in the Box

Following an accident with the TARDIS, the Doctor and Twilight find themselves 1000 years in the future. Here they find a futuristic Equestria, a confused Queen Celestia, and a pony from the Doctor and Twilight's future who wants revenge.

The Doctor suddenly finds himself in the magical land of Equestria and soon discovers that he's regenerated into a pony. As Twilight Sparkle tries to learn more about the Doctor with the help of Spike and Princess Luna, a creature from the Doctor's past arrives in Ponyville with evil intentions.

This story is a sequel to Metroid Equis

With the culmination of events on the BSL Research Station, Samus Aran is finally able to come back to Equestria, Planet Equis; to come back home. Much has changed in her absence, but it is still the friendly, peaceful, welcoming planet and nation that she left behind two and a half years prior. With the Space Pirate threat neutralized and the secret, illegal Metroid militarization programs destroyed, it appears that Samus can finally take another massive breather with her friends and enjoy some well-deserved rest, recovery, and relaxation. The galaxy is finally at peace.

At least... for a short while.

A new enemy, one much closer to home, soon rears its head, threatening all of Equestria and Equis with complete and utter annihilation. Their mission: revenge. Samus will fight with all of her being alongside her allies against an enemy who would like nothing more than to see all that she holds dear, including her home planet, completely razed. In so doing, her cunning, ever determined enemies unleash a weapon so unexpected, so eerily familiar yet horrifically foreign that even Samus herself just might prefer the late Ridley or the SA-X...

Editing Team: Random_Dragon; ToxiClay

The Metroid Timeline/Chronology (confirmed by Nintendo) can be found here.

Canon Considerations
MLP-FiM: Up to AND including "Magical Mystery Cure." (Seasons 1, 2, and 3)
Metroid Series: Everything up to AND including Metroid Fusion (Including original mangas. See official timeline above). So, effectively everything.