A little over a year ago, I made a thread on here about which Warframes would match up best with various MLPG4 characters (mostly focusing on EG, but dipping into FiM as well). Today, I'd like to update this with the Warframes introduced after that point, as well as shuffle around a few picks! I explained it as a "main" last time, but basically I'm performing under the general assumption that each character uses a single Warframe.
Spoilers inbound for those who've not completed all the Story Quests.

The Main Protagonists of EG + a few from FiM:

• Sunset Shimmer: I still feel that she would be paired best with Excalibur Umbra. The way in which you obtain him matches almost too perfectly with Sunset's Geode Power.
• Starlight Glimmer: Standard Excalibur. Because she's Sunset 2.0? (I'm not sure if anyone even remembers that old meme anymore...)
• Applejack: We still don't have any heavily Plant-Based Warframes yet, so I'm sticking to my prior choice of Rhino. AJ's special Geode Magic is highly enhanced strength and durability, and Rhino's whole theme is a powerful tank running in with a battleaxe (regardless of what meta-worshippers say about the actual mechanics).
• Fluttershy: Khora. Fluttershy would be all about those Animal Companions. Heck, possibly even MOAs and Sentinels as well. She'd likely have most of her Plat spent on Companion Slots so she could have as many as she wanted. And you know her Floof collection display would be on-point.
• Pinkie Pie: Previously I picked Mirage as Pinkie's Frame, and I stand by that. There's so much about Mirage (especially Mirage Prime) that screams "Pinkie Pie". But I will accept arguments made in favor of Grendel. There's certainly nobody and nopony else that can match her voracious appetite.
• Rainbow Dash: I stand by my previous decision of Volt. While I can understand the cries of "But we have Gauss now!", I still feel like Volt is the better option. Dash has never purely been about speed. She's been about precision stunts done at high speed. And I feel Volt would be better suited to such a task.
• Rarity: I'm doubling down on my choice of Gara for Rarity; especially now that she's been Primed. You cannot tell me that Rarity wouldn't want to look as elegant as possible while blasting people in the face with a sparkly shotgun and whacking them around with a bejeweld hammer.
• Twilight "SciTwi" Sparkle: Originally I settled on Mag. But I still believe this choice is interchangeable with Princess Sparkle's Frame.
• Princess Twilight Sparkle: Originally, I stuck her with Nova. Again, I believe this choice is interchangeable with SciTwi's Frame.

Cutie Mark Crusaders

• Apple Bloom: This is a tight three-way-tie, but I ultimately choose Vauban. Previously I went with Hildryn, mostly because of the fandom depiction of Bloom growing up to be just as strong as her sister, but I really think I should branch out with AB a little more. She strives to have her own identity, you know. So that left me with one of the Ball Tossers. And I pick Vauban. While I could see Protea as a crafty type, I see that far more in Vauban. And I really feel like Bloom would be all in on the Modular stuff.
• Scootaloo: After some deliberation, I decided to stick with Zephyr. The one thing that Scoots wants more than anything is to fly like Rainbow Dash. Even if she's come to terms with that being a desire she may never fulfill, it's still a part of her. So, despite Zephyr not being that great, I think the BirdFrame is the best fit for Scootaloo.
• Sweetie Belle: I've decided to choose Wisp for Sweetie. I've often seen the fandom portray her as the emotional support of the CMC, so to keep the cute aspect of her while still providing support, I choose Wisp. This is more thought than I initially gave when she got Nezha.

The Dazzlings

• Adagio Dazzle: Hydroid.
• Aria Blaze: Sevagoth.
• Sonata Dusk: Yareli.
• Batch Reasoning: Ever since we got Call of the Tempestarii, I knew what I had to do. Captain Hydroid, First Mate Yareli, and Helmsman Sevagoth! Sailing the Solar Rails to plunder booty and kick in teeth! As a bonus headcanon, Yareli is totally Hydroid's daughter. No question.

The Shadowbolts

• Indigo Zap: Hildryn. I gave a rather BS reasoning for her pick last time (Chroma). But after thinking about it, I bet she'd like Hildryn more. Or I could give Indigo either Ash or Loki, seeing as she somehow disappears when she should still be around.
• Lemon Zest: I once more revert to my previous choice of Banshee. Others would inside upon another Frame, but that Frame was, is, and will always be reserved for someone else in my heart.
• Sour Sweet: Equinox. Like last time, I made note that Sour Sweet seems to be easily able to flip between sounding nice or rude, and made another note that the fandom often depicts her as bipolar. So I think the best way to represent those is a Frame that masters duality.
• Sugarcoat: Trinity. Sugarcoat would definitely be the "I'm the Healer so I decide who lives and dies" kind of player. I'm not sure why I gave her Ash last time. I think it had some reason. But I'm not entirely sure what it was.
• Sunny Flare: Protea. Last time, I gave her Vauban because she wears a Pipboy. This time around, Bloom took that option. But I realized that Protea's a better fit anyway. Sunny strikes me as the kind of girl that would custom order a bodyguard (like Parvos Granum).

The Royals

• Celestia, both versions: The Lotus. Celestia is often referred to as the Mother of Equestria, so who better to pair her with than the Mother of the Tenno? This also works with what we learn of The Lotus and Margulis. I often see Principal Celestia as Margulis, sacrificing a lot in order to help guide children as they grow in their potential. And I attribute Princess Celestia with Natah. The Princess of the Sun holds many secrets, and is reluctant to share them even with her own sister. So who better to represent the idea of The Lotus than the two Celestias?
• Luna: Teshin. Another NPC, I feel like Teshin would be a great fit for Luna; mostly because of Teshin's one character trait of "I object to how The Lotus does things". Plus, poor Teshin is often shoved to the wayside, much like Luna was. So I feel they'd get along well. And who wouldn't want to see Conclave Hyper-fan Luna? Imagine watching her cheer on the Moon Team in a Lunaro match! It'd be too adorable!
• Cadence & Shining Armor: Titania & Oberon. In the source material, Oberon is the King of the Fairies, and Titania is his Queen. I find this to be a perfect fit for the lovebirds of FiM.
• Flurry Heart: I don't really want to include Flurry because she's so young, but for the sake of representation, I'll assign her to Nakak, the merchant girl in Cetus.
• Discord: A "Royal" of sorts, mostly in the fact that he seems to have some form of control over the Chaos Realm. I hate to make him one of the Warframes, but Xaku is too perfect of an aesthetic fit to not pair with him. They're both mish-mashes of multiple things.
• Queen Chrysalis: We don't have a shape-shifter in Warframe yet (and I honestly doubt we ever will), but we do have Nyx; and I'm sure Chryssy would enjoy having Mind Control powers if her usual abilities weren't available to her.
• King Sombra: If I had to assign a Warframe to him, it'd be either Inaros or Revenant. But I feel like a much better fit would be the NPC that's sometimes a DevPC, The Stalker.
• Dragon Lord Ember: I think the obvious choice here is Chroma. Chroma's whole gimmick really fits a Master Dragon.
• King Thorax & Prince Pharinx: I think Nezha for Thorax and Wukong for Pharinx. They have styles that vibe together, and I could see Wukong as the older brother that protects Nezha.

Others

• Gallus: Ash. Gallus just looks like an Anime Dork that's going through their "Edgy Weeb" phase.
• Big Macintosh: Atlas. The biggest and strongest of them all, for the strongest of the Apples.
• Tree Hugger: Baruuk. The hippie pone with the monk. A match made in heaven.
• Smoulder: Ember. NOW we get a Dragon with Ember. XP
• Double Diamond: Frost. Was pretty easy once I remembered that Starlight's villager friends existed.
• Gilda: Garuda. Yeah, she may be nicer now, but don't tell me that she wouldn't go gore queen on you if she needed to.
• Lightning Dust: Gauss. With Gauss' stats and playstyle, I'd imagine that you'd have to be a daredevil to play him. Plus, with the amount of times Dust crashes during her stunts, it fits the 99% of players that run Gauss on standard missions. XP
• Soarin: Grendel. The voracious eater of pies deserves a Frame equally as hungry.
• Juniper Montage: Harrow. I can see Juniper staying in a dead-end job as a form of pennance for hurting her uncle. I can also see her maybe forforming certain little rituals on movie night.
• Ocellus: Ivara. She seems like the kind of individual that's smart enough to use all of Ivara's toolkit. Unlike 99% of players, who spam Prowl and Sniper/Pistol headshots.
• Moondancer: Lavos. To quote his Profile video, "Lavos harnesses the secret of invention, Tenno. Experimentation is the beauty of science." But I would easily accept arguments for Zecora or SciTwi.
• The Great and Powerful Trixie Lulamoon: Limbo. If you need to ask why, you never clicked the link.
• Wallflower Blush: Loki; again, because we have no plant Frames. The ability to become invisible at will is something I'm sure she'd prefer over constantly being in the background. I will accept arguments made in favor of Titania, Ivara, or Banshee. The three of those fit way better, but Zest already has Banshee because of her 4th Ability, and I don't want to repeat Frames.
• Braeburn: Mesa. I don't have a very good reason other than "I wanted to use a Southerner". But it's better than the reason I gave Flash, which was "I wanted to use Flash and nothing else fit".
• Zecora: Nekros. I think we all know by now that Zecora's entire aesthetic draws from old stereotypes of shamanistic figures. And Nekros is directly described as pulling from similar sources. I wanted to give this Frame to someone else, but I can't think of anyone but Zecora.
• Sassy Saddles: Nidus. NOW HEAR ME OUT! I know, I know, it's not exactly the most obvious choice. I'm still not even too sure about this. But think about it. Nidus is The Infestation incarnate. He's the master of the Helminth. And we all know what the Infestation does to you. Now think about Sassy. She's constantly living in a world where it's too easy to lose yourself and become a toxic and highly unpleasant person. But she knows how to navigate through that and actually tries to be a good person. Much like how, though us, Nidus channels his Infestation powers towards a constructive goal.
• Vinyl Scratch: Octavia. If you didn't figure it out before, you now get it. There are so many levels as to why this is so perfect that I can't even go over them all and still have time left in the universe. And if you still can't figure it out, then I can't help you.
• Suri Polomare: Saryn. Speaking of toxicity! What's more perfect than a contender for most toxic personality in FiM using a Warframe that fights with literal toxins?
• Gilda: Valkyr. Now that I've had more time to chew on it, I think Gilda is a better fit for Valkyr than Lightning Dust (though I'll still accept her as an appropriate user). On the Pre-Game Lore side, Valkyr kinda similar to Baruuk; calm and restrained most of the time, but can easily become vicious and violent when she lets loose. On the During-Game Lore side, she was a victim of Alad V's Zanuka Project experiments; and as such is now unhinged and near-feral. Gilda goes through the reverse in her arc. She starts off and rude, confrontational, and prone to potentially violent outbursts, but changes to a much more restrained and kind individual after Pinkie's influence effects her.

And that's the list! I hope you all enjoyed! Let me know what you all think! And should we get any more Frames this year, I may do another update in late December!

Neat.

Some pretty good choices. Nice job man.

I like most of these pairings, though there's one particular one that doesn't quite fit with me. Though, it's more personal than anything else. That one being Wukong and Pharnyx. While it is true that Wukong and Nezha do have styles that work really well together, Wukong is more of a trickster. Heck, trickery is even mentioned in Wukong's description

Descending from the empyrean eternal, the unruly primal saint Wukong wreaks havoc in the System with his immortal trickery and savage beatings.

Reason why... well, I don't recall Pharnyx being a trickster by any means. Sure, all changelings can transform and such, but I don't see Pharnyx playing pranks on people and messing with them like Pinkie Pie would. Though, that's just me, I still like a lot of these pairings and this looks great so far

7527234
Eh, this one's moreso based on how the entire community uses Wukong as a "Rambo type". Drop in, pop 1 Immediately, rampage through the level, 2 your way over to extraction ahead of anyone else that might be with you. Not that it's unfitting. According to the stories, Sun Wu Kong was the best fighter in the land in addition to being a trickster.