From Left-to Right:
Eventide
"I don't know how you accomplished it but somehow you made the Princess of Dreams want to wake up and never sleep again, that takes some serious skills."
Full Title: Her Royal Highness (Princess) Eventide, Somniare Texente Tela (Dream Weaver), Eldest Child of House Storge, First Heir to House Storge.
Parents: Princess Luna, Octavia.
Sibling(s): Moonlight Sonata (Younger Brother)
Species: Alicorn
Special talent: Sleep-based Magic (Sleeping potions, enchanting lullabies, etc.)
Nickname(s): Eve, Eva, Evie, Sleeping Beauty.
Age: 21 years old.
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Wysteria
"If you break a rule, clean up the mess. One mustn't leave broken bits of rules lying about… unless of course, you're me, in which case — I love to leave the shards of my misdoings all about, it brings me joy! …I don't think that applies toward your situation though… look I'm not supposed to be the voice of reason I'm the Princess of Chaos!"
Full Title: Her Royal Highness (Princess) Wysteria, Ischievousmay Owerflay (Mischievous Flower) (Discord doesn't do traditional Latin for his Royal Titles, Pig Latin is funnier!), Eldest Child of House Ludus, First Heir to House Ludus.
Parents: Discord, Queen Trixie.
Sibling(s): Malice, Malediction (Younger Twin Brothers)
Species: Draconequus
Special talent: Flower/Plant-Based Magic/Botany, often does outdoor magic shows and she also later becomes the official go-to for the care and keeping of parks, forests, etc.
Nickname(s): Wisty, The Wonderful and Whimsical Wysteria, Wyndy.
Age: 19 years old.
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Sparkling Dawn
"If there's one thing I've learned from Mother and Father, it's that you cannot love others if you don't love yourself and I think that's why I love so many ponies: I'm awesome!"
Full Title: Her Royal Highness (Princess) Sparkling Dawn, Stella Polaris (North Star), The First and Only Child of House Philautia, Heir to House Philautia.
Parents: Prince Blueblood, Princess Sunset Shimmer.
Sibling(s): N/A
Species: Unicorn
Special talent: Light Magic, specifically spells to guide lost ponies in air/sea ships home (beacon/flare spells, fog clearing spells, etc.) she lives in her own lighthouse and keeps it lit using her magic so military, commercial and personal ships have a way to return to Equestria.
Nickname(s): Dawn, Sunny, 'The Star of The Ocean' (she's not sure if it's meant as a military honorific or if she's just getting hit on).
Age: 17 years old.
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Skywishes
"So what if I don't have magic like most of my cousins, they can't make a fully functional dragon kite with just red construction paper, sticks and a piece of string so I think we're even!"
Full Title: Her Royal Highness (Princess) Mi' Desideri Skyla, Volens Stella (Wishing Star), Youngest Child of House Eros Kai Pragma, Second Heir to House Eros Kai Pragma.
Parents: Princess/Queen Cadence, Shining Armor.
Sibling(s): Brave Heart (Older Brother)
Species: Pegasus
Special talent: Kite Making
Nickname(s): Skyla, Sky, Wishy-Washy.
Age: 16 years old.
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Velvet Shimmer
"I'm cute, yes, it's true. I really can't help it, but what can I do? When you're cute, it just shows! With these two darling eyes and this cute little nose."
Full Title: Her Royal Highness (Princess) Velvet Shimmer, Minimamque Stellata (Littlest Star), Third Child of House Philia, Second Heir to House Philia.
Parents: Princess Twilight Sparkle, Prince Flash Sentry.
Sibling(s): Dusky Skies, Sound Wave (Older Half-Brothers)
Species: Pegasus
Special talent: Jewelry Making
Nickname(s): Vel', Little One/Baby Sister (Dusk and Sound Wave), Little Star (Flash and Twilight).
Age: 10 years old.
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Solstice
"As the Princess of Harmony, I know best how to keep the world harmonious, balanced and peaceful… and that can only be achieved if you SHUT. YOUR. MOUTH."
Full Title: Her Royal Highness (Princess) Solstice, Nocte et Lux (Light and Night), Second Twin of House Agape, Second Heir to House Agape.
Parents: Princess Celestia, (Good) King Sombra
Sibling(s): Reflection (Twin Brother)
Species: Alicorn
Special talent: Keeping Balance and Harmony, eventually becomes the 'Mother of Modern Justice' and updates the Equestrian Judicial system to be more fair and effective.
Nickname(s): Sol, Sel, Sonia, Princess Harmony (Wysteria, Malice and Malediction).
Age: 25 years old.