You are wrong: She is a Ravenclaw.
Slytherin traits she does not have:
1-Traditionalism: Elsa is not into traditionalism and the past in fact in the movie she rejects the past and look forward into the future, remember "Let it go" "the past is in the past" in the songs she is clearly not happy with the traditions how she was supposed to act
2-Leadership qualities: Just because Elsa was born into royalty does not mean that she has leadership qualities. she became the Queen because she was the first born of the King and Queen of Arendelle not because she has leadership qualities.. In the movie she didnt show any signs of leadership and also in the info about Elsa in Disney wiki is not a trait she possess. If there is someone who clearly show leadership qualities in the movie is Hans ( the way he was leading the soldiers when they star searching for Elsa and Anna was the only part of the movie where this trait was shown in the movie) if you want to look for "royal blood" who have leadership quualities in movies and real life then look for "Aragorn" in the lord of the rings movies and Queen Elizabeth I of England
3 and 4-- Ambition and desire for power: absolutely not. if you read about those 2 traits and the Slytherin welcome letter its clearly stipulated that those traits are about to be on top, the best an be a part of the elite in a social hierarchy ( greatness in the words of Salazar Slytherin) and Elsa during the movie never show any sign of wanting any of this also in Disney wiki when reading about Elsa official canon personality she does not have thes traits. If there is someone who clearly shows this traits is Hans (He really wants to be on top and wants the power to be a king)
5-Fraternity: you are clearly mistaken Slytherin Fraternity trait for Hufflepuff Loyalty trait. Slytherin Fraternity as the Slytherin acceptance letter says "once you’ve become a snake, you’re one of ours – one of the elite" Slytherin fraternity is like an exclusive club , while hufflepuff loyalty as the welcome letter say "Hufflepuffs are trustworthy and loyal. We don’t shoot our mouths off, but cross us at your peril; like our emblem, the badger, we will protect ourselves, our friends and our families against all-comers. Nobody intimidates us" is clearly a Elsa trait also is a canon elsa trait in Disney wiki.
In fact the only Slytherin traits she possess are Determination,Resourcefulness and Self- preservation meanwhile she possess all of Ravenclaw traits (Intelligence, Wit, Wisdom, Creativity,Originality, Individuality and Acceptance) she has enough wisdom to know that the Anna/Hans Marriage was stupid and also wisdom enough to know tht the answer to stop the eternal winter was love.
Also you got to be kidding saying that her Ravenclaw traits are secondary. her most important traits are Loyalty (Hufflepuff), Acceptance (Ravenclaw), Intelligence and love of learning (Ravenclaw), Individuality (Ravenclaw) and Determination (Slytherin).
1-Loyalty (Hufflepuff) clearly a main Elsa trait
2-Acceptance (Ravenclaw) listen to the song "Let it go" and at the end when she ends the winter when she finally accepts herself and her true nature and as the ravenclaw welcome letter say "we think you’ve got the right to wear what you like, believe what you want, and say what you feel. We aren’t put off by people who march to a different tune; on the contrary, we value them!"
3-Intelligence and love of learning: Again listen to the songs let it go "It's time to see what I can do To test the limits and break through" then at "My soul is spiraling in frozen fractals all around…" and then look at this "official Canon image" of one of frozen Disney stories where she clearly loves to learn about Geometry media.tumblr.com/10d4365a99b9e… Geometry is used a lot in architecture and construction, as knowing what shapes to use plays an important role in making sure a building is structurally sound. The very first thing Elsa does when making her castle is creating a center point to ensure the structure will be balanced. (I am a Civil Engineering student and i know about this) so she basically uses herRavenclaw intelligence, wit, creativity and originality to build the ice castle silvermoon424.tumblr.com/post/…
Elsa uses the term “Fractals" in "Let it Go" ("My soul is spiraling in frozen fractals all around…"). A fractal is a geometric term that describes a set that displays a self-similar pattern and is often used to catalog snowflakes. The fact that Elsa knows and uses this word really speaks volumes about her knowledge and love of geometry. (Again i am a Civil Engineering student and i know about this) silvermoon424.tumblr.com/post/…
4- Individuality:A trait that goes hand in hand with another Ravenclaw trait "Acceptance" listen to the song "Let it go" when she finally accepts herself and her true nature and as the ravenclaw welcome letter say "Another cool thing about Ravenclaw is that our people are the most individual – some might even call them eccentrics. But geniuses are often out of step with ordinary folk, and unlike some other houses we could mention, we think you’ve got the right to wear what you like, believe what you want, and say what you feel. We aren’t put off by people who march to a different tune; on the contrary, we value them!"
5-Determination (Slytherin): to keep those years in isolation she needs a lot of determination
Her other traits: Kindness, Patience (Hufflepuff), Wisdom, creativity, wit, Originality (Ravenclaw), Self-preservation and Resourcefulness (Slytherin) are secondary traits