Have you noticed that the most important student protagonists of the latter books, aka the six who went to the Department of Secrets, roughly correspond with the Elements of Harmony?

Harry is the Element of Generosity. He is willing to devote his entire life to helping others, including those who fight him or otherwise don't deserve it. He willingly gives up time and resources to help others, shares his secrets with his friends and those who need it, and is all but selfless when the occasion arises.

Ron is the Element of Loyalty. He is Harry's truest friend, and even though he has trouble trusting his friends at points, he is always the one to take the blame for the falling out. Sure, he left Harry in tight spots, but he always came back of his own accord, and when he was needed.

Hermione is an obvious match for the Element of Magic. She is the same kind of heroine as Twilight Sparkle, and has some very similar character arcs. Honestly, I don't think I need to explain it.

Neville is the Element of Kindness. He is reluctant to hurt others, even when the situation calls for it. Much like Fluttershy though, his breaking point is when innocents are hurt. Remember what got him into deep shit in the exposition of Book 7? It was saving a student who was wrongly being punished. Furthermore, also note his gentle demeanor around dangerous plants, similar to Fluttershy's behavior around animals.

Ginny is the Element of Honesty. This may seem like a weird choice, especially considering the fact that she lies, but think about it from a different angle. Ginny's defining personality trait throughout the series was her love of Harry Potter. She was a full 3 dimensional character, but that was what remained constant about her. And she never denied it to herself. Ginny was always honest with herself about her desires and goals, and rarely hid her motivations.

Luna is the Element of Laughter. Despite having a hard life and being ridiculed, she always maintains a positive attitude. Considering how grimdark her life seems to be, her positive demeanor is impressive to say the least.

Just a thought.

Eh, kind of works. Never been a fan of human versions of the elements, and having it be characters from a book roughly jammed into what they somewhat correspond to doesn't really help.

It does work (though I am unsure about Ginny, another alternative would be Sirius Black - he survived Azkaban because he was innocently imprisoned - then again, he is dead. Mc Gonagall would also work) but where do you plan to go from there? Are they showing up in Equestria or do the ponies show up on earth in search for the corresponding elements?

759675 Who said the story had to go anywhere? One of my favorite kinds of crossover stories are those where two characters talk about their lives with each other, including what's similar and different. In this case, you could have a random portal to Equestria/Hogwarts sort of deal as an excuse to make characters talk to their counterparts.

True, this kind of story isn't very dramatic. But sometimes, you don't need drama. You just need two characters talking about life.

759639 I'm doing a crossover where Twilight (and Spike, and their pets) get displaced to the Potterverse. In order to avoid character overlap, I basically had to have Hermionie move to France (it's a common thing for Brits to do, actually, to move to the south of France - especially, in stereotype, well-to-do professionals... like dentists.)