Given the massive shipping base of My Little Pony: Friendship Is Magic, there are quite a few One True Threesomes:
- Spitfire/Soarin/Rainbow Dash has a number of supporters .
- Apple Bloom/Sweetie Belle/Scootaloo. Cutie Mark Crusaders OT3, YAY!
- It's also possible to toss in an additional character or two to said OT3.
- Related to the CMC, Spike/Sweetie Belle/Apple Bloom, for those who can't decide between Spike/Apple Bloom and Spike/Sweetie Belle. Spike/Sweetie Belle/Scootaloo isn't as big but does exist. And then there's CMC/Spike.
- Considering all of the Mane Six can be shipped with each other, any combination of any three (or more) of them is viable enough that one can make it work if they try.
- Applejack/Rainbow Dash, Applejack/Rarity, Rainbow/Fluttershy, Rainbow/Twilight and Rainbow/Pinkie, are some of the most prolific ships of the six. Combine them however you wish.
- Discord/Queen Chrysalis is already a semi-popular Unholy Matrimony pairing, and some add Nightmare Moon to the mix as well.
- Princess Cadence/Shining Armor/Queen Chrysalis. If one is into Incest Yay Shipping, then Princess Cadence/Shining Armor/Twilight might count too.
- Celestia/Twilight/Luna, if you can handle the princest that usually goes along.
- Spike/Rarity is a running Precocious Crush subplot; add in Twilight, Coco Pommel, or any other potential love interest for one of the two as needed.
- Any and all three-way ships between Twilight's Evil Counterparts/Foils, — Trixie, Starlight Glimmer, Sunset Shimmer, Moondancer, Sci-Twi (the human world Twilight), and Tempest Shadow — are plausible.
- Twilight and Sunset Shimmer were already a popular ship when Friendship Games brought in Sci-Twi and the Equestria Girls franchise shifted focus from the pony Twilight to the human one. Some fans likewise jumped ship, while others just shrugged and started shipping all three of them, dubbed "Sunset Twiangle."
- Trixie and Starlight became close friends in Season 6 and the shipping for them took off like mad, allowing that threesome with Twilight. Then Trixie became friends with Sunburst, the other main ship Starlight is involved in, and that threesome became feasible.
- Seeing as Sunset and Starlight are both, in a sense, Twilight's "students" in friendship, it's logical shipping for them would spring up. Then they met and became friends in "Mirror Magic", strengthening the idea.
- The human Trixie and Sunset became friends in "Forgotten Friendship", inviting shipping the two of them with either Twilight, or with Starlight Glimmer.
- While it isn't as big as the above due to Flash Sentry being The Scrappy to a large part of the fanbase, he's Sunset's ex-boyfriend and Twilight's Love Interest in the first two Equestria Girls films, so naturally fans had the idea to ship him with Sunset and either of the two Twilights, or even both Twilights. Adding Sci-Twi's canonical love interest Timber Spruce allows more combinations.
- Rainbow Rocks had the Sirens Adagio, Sonata, and Aria as an trio of villains. The shipping was inevitable from the start.
- Both Ember and Thorax were shipped with Spike since their respective first appearances, so once the two became friends in "Triple Threat", Ember/Spike/Thorax shipping ensued.
