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. Since they are known to randomly fall from the sky, they may also live up in trees.
It only drinks morning dew, found under plants' leaves, as well as its own.
This Pokémon was unavailable prior to Generation I.