There's really no costumes that are similar to the Grimhilde outfit (closest thing is the purple-black outfit during the Apple scene).
But to have the episodes that chronicle the fairytale in flashbacks...
Bleeding Through - the meeting of the King and Queen (Snow's parents)
The Queen Is Dead - the death of the Queen
The Stable Boy - the meeting of Snow and Grimhilde (Regina)
We Are Both - when Grimhilde learns magic
Fruit of the Poisonous Tree - the death of the King
The Heart Is A Lonely Hunter - Grimhilde sends Humbert the Huntsman after Snow
The Evil Queen - Grimhilde disguises herself in order to kill Snow White
Snow Falls - Snow meets Florian (David) and they fall in love
7:15 A.M. - Snow meets the Seven Dwarves
Heart Of Darkness - we see Homemaker Snow
An Apple Red As Blood - Snow eats the poisoned apple
The Cricket Game - Snow and Florian sentence Grimhilde to death
Pilot - the s**t hits the fan