Sunkern is a mostly yellow, seed-like Pokémon with a small sprout growing out of its top. It has no visible arms or legs. Sunkern has triangular spike-like protrusions on top of its head, encircling the sprout. Sunkern's body has three broad brown vertical stripes. Two of the stripes start jaggedly above Sunkern's dark eyes, continuing downward. The other stripe is directly below Sunkern's mouth. Since Sunkern's eyelids are brown, the brown streak patterning appears uninterrupted when Sunkern’s eyes are closed.
At this stage of development, it is (statistically speaking) the weakest Pokémon in the game, with a base stat total of only 180. Although it has been stated that its only means of defending itself is violently thrashing its leaves at the attacker, it is capable of using a variety of Grass-type moves.
Sunkern have a tendency to fall from the sky on early mornings, though usually without any predictability. Sunkern tries to move as little as it possibly can, since it tries to conserve all the nutrients it has stored in its body for evolution. A year after a cold summer, the population of Sunkern explodes.
Sunkern are commonly found in Kanto and Johto, but there have also been sightings in Sinnoh. They have also been imported to the Hoenn Safari Zone.
Since they are known to randomly fall from the sky, they may also live up in trees.
A group of Sunkern appeared in Zoroark: Master of Illusions as a few of the many local Pokémon who lives in Crown City. Some took part in surrounding Zorua in the park along with the other Pokémon to prepare to attack him, angry at Zorua for what Zoroark did to the city. Before a fight broke out, the Sunkern, along with the other Pokémon, were calmed by Celebi.
Sunkern tries to move as little as it possibly can. It does so because it tries to conserve all the nutrients it has stored in its body for its evolution. It will not eat a thing, subsisting only on morning dew.
Sunkern has the lowest base stat total of all Pokémon, with a total of 180 points.
Sunkern shares the same species name as Bulbasaur and its evolutions. They are all known as the Seed Pokémon.
Sunkern's official artwork more closely resembled its Shiny form in Gold and Silver than its regular form. This was somewhat rectified in Crystal, although the artwork was still more similar to its Shiny sprite; this discrepancy was fully rectified in Generation III.