Depiction in the series
|Eyes||Dark grayish tangelo|
|Coat||Light goldish gray|
| Cutie mark|
|Voice||Tabitha St. Germain|
|Mane||Light brilliant orange|
|Magic aura||Pale, light grayish cerulean|
| Cutie mark|
The two are first introduced as newborn foals in the episode Baby Cakes, where the ponies visit them in the 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 "monthiversary". Despite being only one month old, Pound Cake and Pumpkin Cake are already able to run around the house. This is true with young ponies in real life who are usually able to walk hours after being born. 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 in Baby Cakes, they also prove the adult ponies' warnings from the beginning correct. 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; and Pumpkin Cake uses unicorn magic to levitate herself, phase through a laundry basket Pinkie Pie has trapped the two under, and break chains Pinkie had locked a toy chest with.
Eventually, it is Pinkie Pie who breaks into tears when she realizes she cannot keep the foals under control. Only then do the babies stop playing around; 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 on 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.
Pound and Pumpkin Cake can fly and use magic, respectively. However, Scootaloo and Sweetie Belle have never used these abilities despite being years older, and the twins haven't been shown using their powers since Baby Cakes.
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 Cake twins appeared briefly again in Ponyville Confidential, throwing a tantrum which was photographed and later featured in a "Gabby Gums" column of the Foal Free Press.