Pound Cake and Pumpkin Cake

Pound Cake and Pumpkin Cake are Mr. and Mrs. Cake's fraternal twin foals who make their debut in the episode Baby Cakes.

Season two
The two are first introduced as newborn foals in the episode Baby Cakes, where Twilight Sparkle, Rarity, Fluttershy, Rainbow Dash, Applejack, and Pinkie Pie visit them at hospital. They are surprised to find out that Pound Cake is a male Pegasus and Pumpkin Cake a female unicorn, despite the fact that their parents are both Earth ponies. Mr. Cake explains by referring to distantly related unicorns and Pegasi in his and Mrs. Cake's family trees. Rainbow Dash, Twilight Sparkle, and Rarity caution the Cakes that young unicorns can exhibit bursts of magical power and that young Pegasi can be quite a handful once they learn how to use their wings.

The next scene shows the toddlers playing with Pinkie Pie on what she calls their "month-i-versary." Despite being only one month old, Pound Cake and Pumpkin Cake are already able to run around the house. That same day, the Cakes are also in need of a babysitter, and after Twilight Sparkle, Applejack, Rainbow Dash, Rarity, and Fluttershy decline the offer, they reluctantly ask Pinkie Pie to take care of the foals while they deliver a catering order.

This proves more difficult and less fun than Pinkie had expected. Her attempts to calm the foals when their parents leave, including trying to feed or bathe them, all end with the babies crying. Each time Pinkie can calm them only by emptying a bag of flour over her head, which amuses the foals greatly, but is a huge pain for Pinkie, especially in one scene where Pinkie Pie attempts to give the two foals a bath, and, as a last resort, ends up dumping another bag of flour on top of her head. Pinkie has become very wet while trying to give the twins a bath, and the flour mixed with the water ends up creating a sticky, doughy mixture on top of Pinkie's head.

Later, they also prove Twilight Sparkle and Rarity's concerns from the beginning valid. Pound Cake makes it difficult for Pinkie to chase after him when he starts flying and walking on the ceiling with the help of his wings, whereas Pumpkin Cake uses unicorn magic to levitate herself, phase through the laundry basket Pinkie Pie that trapped the two under, and break chains which Pinkie locked a toy chest with.

Eventually, Pinkie Pie breaks into tears when she realizes she cannot keep the foals under control. Only then do the babies stop playing around and feel guilty for their behavior. They attempt to cheer Pinkie up by imitating what she did to amuse them; emptying a bag of flour over their heads. The next scene shows them peacefully sleeping in their crib, giving Pinkie the opportunity to clean up Sugarcube Corner before their parents come home.

Pound Cake displays a habit of pounding on things and Pumpkin Cake has a habit of chewing on objects that aren't food, including a table cloth, a towel, and several toys. She also tries to chew on a broom stick that Pinkie Pie uses. Pumpkin Cake is also the first unicorn to be seen levitating herself.

The foals say one word each in Baby Cakes, spoken by Andrea Libman and Tabitha St. Germain: Pound says "Pinkie", followed by Pumpkin saying "Pie..."

Pound Cake and Pumpkin Cake make a brief appearance in the opening of the episode A Friend in Deed, watching Pinkie Pie do some sort of aerobic exercises. Initially unamused by Pinkie Pie's attempts to coax them into laughter, they become amused after Pinkie Pie manages to get into an accident, mirroring their behavior in Baby Cakes.

The twins appear briefly again in Ponyville Confidential, throwing a tantrum which is photographed and later featured in a "Gabby Gums" column of the Foal Free Press.

Season three
Pumpkin Cake, without her brother, makes another brief appearance in Magic Duel, sitting on a makeshift throne made by her parents, who are enslaved by Trixie at the time.

During Magical Mystery Cure, Pound Cake appears in one of Pinkie Pie's flashbacks.

Season four
In Pinkie Pride, the Cake twins appear briefly during Pinkie the Party Planner, popping their heads out of their stroller as Mr. and Mrs. Cake walk through town. They are stated to have been named during a foal shower that Pinkie Pie had thrown for their parents. They also appear in Filli Vanilli watching the Pony Tones perform at Sugarcube Corner.

Season five
In Slice of Life, Pound and Pumpkin appear with her parents as they transport the wedding cake to Cranky Doodle Donkey and Matilda's wedding, and they appear during the ceremony.

IDW comics
Larry's Comics and Jetpack Comics exclusive Covers RE of depict 5-bit-denominated Equestria postage stamps that each feature Pound Cake or Pumpkin Cake. In a panel in, they appear in baby bags that are strapped onto their parents. In, they are left in the care of Big McIntosh when Mr. and Mrs. Cake leave to deliver a cake. He takes them to see a puppet show put on by Trixie.

In the Friends Forever series, Pound and Pumpkin appear at Sugarcube Corner with their parents on page 4, and Pumpkin appears with her parents and Rarity on  cover A.

Twilight Sparkle and the Crystal Heart Spell
Pumpkin Cake and Pound Cake appear in chapter 2 of the book Twilight Sparkle and the Crystal Heart Spell, "A Foal House". They say "Giddyup!!!"

The Elements of Harmony guidebook
''THE CAKE FAMILY are the proud owners of Sugarcube Corner, Ponyville's most delicious bakery. The store is run by the kindly MR. CARROT CAKE and his wife, MRS. CUP CAKE, who make the tastiest sweets for every occasion. Pinkie Pie loves working in the bakery and often watches over the Cakes' twin foals, POUND CAKE and PUMPKIN CAKE.''

Merchandise
Pound Cake and Pumpkin Cake miniature collectibles are included in an upcoming character collection set.

Quotes

 * Baby Cakes
 * Pound Cake: Pinkie...
 * Pumpkin Cake: Pie...

"Giddyup!"

- Twilight Sparkle and the Crystal Heart Spell