Nurse ponies

Nurse Snowheart, Nurse Sweetheart, Nurse Tenderheart, and Nursery Rhyme are a group of female Earth ponies who work as nurses at Ponyville Hospital. They are unnamed in the show, "Nurse Sweetheart", "Nurse Tenderheart", and "Nursery Rhyme" being placeholder names, but Nurse Snowheart is named in merchandise.

Designs
Nurse Snowheart has a yellow coat, two-tone light blue mane and tail, green eyes, and a cutie mark of a white cross with a pink heart on each corner. She resembles S04E20 Unnamed Earth Mare #1 in color scheme and eye style.

Nurse Sweetheart has a pink coat, light purple and white mane and tail, deep blue eyes, and a cutie mark of a white cross with a pink heart on each corner. She shares her body design with Mrs. Cake and Cookie Crumbles (except her horn), and she shares her color scheme with Diamond Tiara.

Nurse Tenderheart has a bluish gray coat, light green mane and tail, purple eyes, and a cutie mark of a red cross. She shares her design with Nurse Redheart and an Earth pony mare shown on Hasbro's My Little Pony Facebook page, and she resembles G1 Nurse Tenderheart.

Nursery Rhyme has a gray coat, dark red mane and tail, purple eyes, and a cutie mark of a white cross with a pink heart on each corner. She shares her design with Twist.

Season one
In Applebuck Season, Nurse Tenderheart appears at Ponyville Urgent Care, tending to ponies who suffer from food poisoning after eating Applejack and Pinkie Pie's "baked bads".

Season two
In Read It and Weep, Nurse Sweetheart first appears pushing a bookmobile outside Rainbow Dash's hospital room. She later dismisses Rainbow's friends from the room when visiting hours are over. Later in the episode, Nurses Sweetheart and Snowheart cart Rainbow Dash out of bed and in a wheelchair when she's discharged from the hospital.

When Rainbow Dash sneaks back into the hospital to read the rest of Daring Do and the Quest for the Sapphire Stone, the hospital staff catches her and mistakes her for a thief. When the filly Nursery Rhyme attempts to block Rainbow's path, Rainbow simply flies over her. Nurse Sweetheart then chases her across Ponyville alongside Doctor Horse, Night Watch, and Screwy.

Season three
In Just for Sidekicks, Nurse Snowheart appears talking with Screwy in front of her house.

Season four
In Inspiration Manifestation, Nurse Tenderheart appears without her nursing cap, shielding her eyes from the glare of Rarity's "improved" gold-covered roads. Tenderheart appears again in Equestria Games, with her nursing cap again, as a spectator of the titular event at the Crystal Empire.

Merchandise
A mini-figure toy and a collector card of Nurse Snowheart are packaged together as part of the ninth wave of mystery packs. According to the card, she "is always ready to lend a helping hoof!" Her name comes both from the card and from the packaging of the wave, which each list the name as a trademark. A November 6, 2013 "vorläufige Abbildung" image for mystery packs also includes her.

Nurse Sweetheart is shown on Acidfree's first art print.

Quotes
"All right, my little ponies. Rainbow Dash needs her rest. You'll have to come back tomorrow."

- "Nurse Sweetheart", Read It and Weep

"Okay, now, dinner time for Rainbow Dash."

- Nurse Snowheart, Read It and Weep

"Good day, Rainbow Dash."

- "Nurse Sweetheart", Read It and Weep

"Take care!"

- Nurse Snowheart, Read It and Weep

"Stop, thief!"

- "Nurse Sweetheart", Read It and Weep