Alright members, here is a good question. In your own headcannon, what would happen to the mane six if they appear in Mareth and what will be there transformations?

4139582
Twilight : Kitsune
Rarity : Succubus
Applejack : cowgirl(no pun)
Pinky Pie : Slime
Raindbow Dash : harpy
Fluttershy : Dryiad(I think not really sure)

4139640
I can see that. Twilight, being the magic genius she is, would not only focus on light and black magic, but also focuses on other forms of magic, like fox magic. Rarity being a succubus is not far, the only difference is that she may or may not have the ability to fly, and have larger breast. Applejack as a La Bova AKA Cowgirl, well I guess working on Whitney's farm and helping Marble compels her to become one. Pinkie Pie as a slime girl, I need some help on that one. Rainbow Dash, yeah I see her flying through the air, not wanting to sacrifice her ability to fly. Fluttershy as a Dryad, yeah, I can see her becoming one.

4139907 well not a slime per say, but like that cake golem girl in town

In my Headcannon,
Twilight Sparkle would master most magic in Mareth, maybe a few mutations here and there as she discovers the various transformative items, and maybe friends with Rathazul.
Applejack would become a Level 3 or 4 Horse Morph or a centaur [internally laughing imaging her freaking out as she looks like Tirek], helping Whitney's farm, but also seeing her teaching Kelt a lesson on manners.
Rarity, maybe a Harpy/La Bova hybrid, herself showing her large beautiful wings to everyone, maybe finding a way to show off her new figure, and being smitten by a certain thief.
Pinkie Pie...... I actually having a hard time trying to imagine her becoming something, with her random nature and 'Pinkie Sense' alerting her to everything.
Rainbow Dash, maybe a Goblin or Goblin/Succubus hybrid, knowing her that she values her speed and maybe always having loose relationships.
As for Fluttershy, maybe a Succubus Paladin Maiden, [Scandalous! A demonic virgin, learning the ways of good.] helping everyone while trying to keep her purity. I see her helping the Bee and frog girls, acting motherly with the fox girls, and maybe forming a relationship with a certain fire breathing Demigod.

4139926
Ohhhhhhh, okay, I see now.

If they don't all appear together
Applejack - Dog Girl - Helps on the farm
Rainbow Dash - Dead - Killed by something she fucked with too early like tentacle beasts.
Rarity - Slave - Whine all you want, the omnibus loves it.
Twilight - Either managed to get end game or succombs to the pleasure, hard to tell with her. I'd guess she'd get small transformations from the food items like Whisker Fruit.
Pinkie Pie... overthrows Lethice. New demon queen is on the rise.
Fluttershy - Ceraph's slave at best.

4140359
Hahahahahah! That is good!

if they were all humans at the start

Pinkie Pie = Pony from the april fools transformation

if they were all ponies from the start

Pinkie Pie = Pony from the april fools transformation

4140765
God help the demons if that happens.

4141236 so do you agree that is what would happen with pinkie? i only say that cause its completely random and fitting

4141620
Yep.