Appletun is a dragon-like Pokémon whose body is reminiscent of apple pie. It is mostly green with a yellow underside and lower jaw, and it has an orange spot on its chest that resembles an apple core. It has a piece of an apple on its head worn as a helmet. Its leaf-like eyestalks usually droop down from under the apple helmet as though they were ears, but may be lifted up to reveal small beady eyes. It has black slits for nostrils on the tip of its muzzle. It has a large hump on its back with several overlapping stripes that resemble an apple pie's crust on top, along with a pair of red and green leaves. It has four short, bulky legs with paws, and a stout tail.
Appletun's body is caked in sweet nectar, whose smell attracts Bug-type Pokémon which Appletun preys on. However, Appletun's primary diet is sweet apples. In order to ward off other Pokémon such as Lechonk from licking the nectar on its back, Appletun can spew a sticky nectar. The skin on its back is said to be tasty, and children used to eat it as a snack.
Appletun is the only known Pokémon capable of learning the move Apple Acid. Appletun and its evolutionary relatives are also the only known Pokémon that can have Ripen as an Ability.
When exposed to Gigantamax energy, Appletun's body changes, becoming larger and stouter. A giant apple engulfs most of its body, leaving only its head, neck and tail exposed. Its leaf-like eyestalks stand up straight and it has a piece of the apple covering its head, with yellow carvings on it resembling nostrils. Its cheeks are rounded and it hangs its mouth open, letting its red tongue loll out. Its neck becomes taller and stretches upwards, while its tail becomes elongated and wraps around the base of the apple. Three red clouds float around its neck. Gigantamax Appletun and Flapple are physically identical.
The sweet nectar that covers Appletun's body overflows from the top of its apple after Gigantamaxing, and it increases in thickness as well, allowing it to absorb more damage than normal. Gigantamax Appletun can shoot out massive amounts of nectar, enough to drown its opponents. Gigantamax Appletun is the only known Pokémon capable of using the G-Max Move G-Max Sweetness.
- Appletun and Flapple are the only Pokémon to have physically identical Gigantamax forms, although they are still treated as different Pokémon as they have distinct Pokédex entries, G-Max Moves, and cries.
- This is also the only instance of two different species of Pokémon that can be physically identical without the use of Transform, Imposter, or Illusion.
- Appletun and its evolutionary family:
- are the only Pokémon that are in the Grass and Dragon Egg Groups.
- require only 600,000 experience points to reach level 100, the lowest among Generation VIII Pokémon, and the lowest among Dragon-type Pokémon along with Altaria.
- Despite requiring the Sweet Apple to evolve from Applin, Appletun's signature move, Apple Acid, specifies it uses tart apples to attack.
Appletun, like its evolutionary relatives, appears to be based on the popular image of a worm burrowing into an apple, as well as a pun on the wyrm, a type of dragon — hence its Dragon typing. Visually, Appletun is similar to reptiles such as tortoises, while its back resembles desserts like the apple pie or the apple turnover. Appletun may also be based on the tale of Bel and the Dragon, about a dragon that bursts open after being fed a cake.
Appletun's Gigantamax form appears to be based on a caramel apple or a candy apple. Appletun and Flapple having identical Gigantamax forms may be a reference to convergent evolution, which can lead to separate organisms independently developing identical characteristics and body plans.
Appletun may be derived from apple, Appleton (a toponym denoting a place where apples grow), ton (unit of weight, referencing its bulk), apple turnover, and under.
Tarupple may be a combination of tart, 怠い tarui (sluggish), たっぷり tappuri (onomatopoetic word for plenty), and apple.