So yes, this is a recolor of Pinkie, but that's on purpose - she's an alternate universe version, not an entirely new character.
"BooBerry Pie knows life’s no fun without a good scare. She keeps Ponyville’s inhabitants on edge with a constant barrage of terrifying pranks which are only occasionally deadly. She's not evil, she just likes creating excitement by making folks jump and shriek with fearful surprise instead of with joyful surprise. Got to love that adrenaline rush!"
The best part of Nightmare Night is slaughtering and eviscerating the pumpkins . . . especially when you light them with your friend's souls in place of boring old candles. (don't worry, she'll give them back in the morning, and in the meantime her friends have the most convincing zombie costumes ever!)