Leafeon is a quadrupedal Pokémon that is feline in appearance, with a short catlike muzzle, brown eyes with slit pupils, and a small black triangular nose. Its coloration is similar to that of a Siamese cat. Its fur is mainly a yellowish cream hue, with brown paws and feet. The body of a Leafeon is slender and limber. Its tail and ears resemble torn and tattered leaves, and the interior part of its ear is brown in color. Besides the leaf-like ears and tail, there are a multitude of smaller leaves growing from their bodies; leaves grow out from the knee joint areas on the forelegs and hind legs, its chest and its back. A larger, curled leaf grows from the middle of its forehead and is the same soft-green color of all the other leaves.
According to the Pokédex, Leafeon employs photosynthesis on top of its animal capabilities, as a result, it is always surrounded by fresh air.
Most of its behavior is unknown. The only trainer who took it on was Zoey, appearing only in a Japanese episode of the anime called Pokémon Diamond & Pearl. It is soon to air on American screens. In the Pokemon PlatinumPokédex, it says it does not fight. Leafeon displays catlike behavior, such as licking its paw and using it to groom its ear (seen in one of its Pokemon-Amie animations). Its cry sounds like a cat's meow.
According to the Diamond and Pearl Pokédex, Leafeon and Glaceon's footprints are the same (this may be related to the fact they both evolve under similar conditions, leveling up near a special rock).
Like Espeon, Leafeon has a type-disadvantage against its evolutionary counterpart (Umbreon and Glaceon respectively). The psychic-type Espeon is weak against the dark-type Umbreon and the grass-type Leafeon is weak against the Ice-type Glaceon. Interestingly both Espeon and Leafeon are associated with the sun and moves relating to it, as Espeon is the Sun Pokemon (and learns Morning Sun via leveling up and Sunny Day via TM) and Leafeon uses the sun for photosynthesis (and learn Sunny Day & Synthesis via leveling up and Solar Beam via TM).
Unlike Espeon, Leafeon does gain a type-advantage against one of the evolutions of Eevee, as the Water-type Vaporeon is weak against Leafeon's grass-type.
In addition to Glaceon, the Leafeon has a type disadvantage against the Fire-type Flareon. This makes Leafeon and Vaporeon (as Vaporeon's water-type is also weak against to the Jolteon's Electric-type) the only evolutions of Eevee weak against the types of 2 evolutions of Eevee while they are also strong against at least 1 evolution of Eevee (Leafeon is strong against Vaporeon, while Vaporeon is strong against Flareon (which is strong against Leafeon).
Both Leafeon and its counterpart Glaceon are weak against Flareon.