Sonata Dusk

In Equestria, the sirens' true appearance is a Hippocampus. Upon releasing their full powers in the human world, the Dazzlings are shown to possess translucent fin-like wings in their anthro forms, unlike their true forms. Their siren forms are summoned as astral projections from their pendants and used to weaken the Rainbooms.

Arriving at Canterlot High, Sonata takes the appearance of a slender teenager with pale sky-blue skin, magenta-pink eyes with cyan upper-eyelids, and long, turquoise-blue hair with dark royal-blue streaks, kept into a high-ponytail with V-shaped bangs by a dark royal-blue hair tie. She dresses in a dark magenta vest with a brighter-colored popped-collar and cuffs, three pale sky-blue buttons with straps, and a light blue musical note surrounded by a brighter-magenta patch on the right side. She also wore a lavender-pink denim skirt, similarly-colored knee-high socks, and similar-length bright magenta high-tops with white soles and toes.

Sonata accessorizes with magenta bracelets with pale sky-blue spikes on both her wrists, and a black choker with a ruby pendant around her neck.

In the film, Sonata and the other Dazzlings are introduced in the human world. They are sirens from Equestria who were banished to the human world by Star Swirl the Bearded before they could conquer Equestria with their dark magic. They first appear in a café causing tension between the patrons, and Sonata briefly argues with Aria Blaze. She and the Dazzlings later convince the students with their music to turn the friendly Musical Showcase into a Battle of the Bands.Sonata and the Dazzlings use their siren's songs to control the students' opinion and advance through the competition bracket. In the final battle against the Rainbooms, Sonata and the Dazzlings are eventually defeated, and the gem pendants with which they controlled the students are destroyed. As a result, their inability to sing leads to them being chased off in disgrace.

Aside from flashbacks, Sonata's true form is never physically shown in the film, but she and her fellow band members gain pony-like ears, extended ponytails, and translucent fin-like wings. They also summon astral projections of their siren forms from their pendants.

A drawing of Sonata's siren form is briefly seen in Friendship Games during the CHS Rally Song. Her siren form can also be seen in one of the human Twilight Sparkle's photos.

Sonata Dusk, alongside Adagio Dazzle and Aria Blaze, make their return in the music video Find the Magic, performing at the Starswirled Music Festival and singing about adjusting to life without their magic.

Throughout Rainbow Rocks, Sonata Dusk is shown to be somewhat air-headed and carefree, similar to Pinkie Pie. For example, before the Dazzlings sing Battle in the cafeteria, Sonata is more focused on getting lunch since it is Taco Tuesday. Also, she and Pinkie are the only ones who actually seem to enjoy Snips and Snails' rap performance. Sonata doesn't pick up on Adagio's sarcasm when she says she "loves" the human world, and she speaks candidly with Sunset Shimmer about her and her friends' true nature, nearly blowing their cover. In addition, she frequently argues with Aria Blaze over trivial matters. Despite this, she can be just as cruel and devious as her bandmates, if at times unintentionally so, as evidenced in her interactions with Sunset Shimmer and Trixie.