What would their regenerated selves be like, how would their friends and family members react, would they still be friends?

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They would resemble the original designs Lauren Faust had for them - G1 Twilight, G1 Applejack, Surprise, Firefly, Posey and Sparkler.

"This is going to bring up all kinds of questions." Twilight Sparkle looked at Applejack, then at the former Applejack sprawled out on the rocky valley floor. "I mean are you still really my friend, Applejack? Should we just treat this as a change of clothes, or are you a brand new pony?"

"Ah feel just like ah did before," said Applejack, or at least the one that was alive. She picked the hat up from the valley floor and made to put it on her head, only to stop when it hung up on the horn. "Well, almost," added Applejack with a cross-eyed look at the new bodily appendage.

"Not quite," said Rarity, who had begun to study a rock on the nearby valley wall. "There's just one more thing you're going to need."

"Pants," declared Pinkie Pie with a look underneath her friend. "Look at the bright side. You'll know how your brother feels now."