Leech Seed (move)/Effect/Generation I

Leech Seed plants a seed on the target. After a target under the effect of Leech Seed takes its turn, 1/16 of its HP will be drained (rounded down, but not less than 1), and the same amount of HP will be restored to the target's opponent (even if it was not the Pokémon that originally used the attack). Recurrent Leech Seed draining will not occur if the seeded Pokémon defeats the target. Unlike other types of damage, the recurrent damage done by Leech Seed can exceed the target's current HP. Leech Seed will not work against Pokémon, and attempts to seed an already-seeded Pokémon will fail.

Leech Seed draining will occur even if the seeded Pokémon knocks itself out with crash damage, recoil damage, or self-inflicted confusion damage, or by making a before the end of its turn. Draining from Leech Seed is done after continuing partial trapping damage and recurrent poison or burn damage. Leech Seed can be removed by or switching. If the target is seeded during a round that it switches in, it will take recurrent damage during that round, but only if its speed is less than or equal to the user's speed.

If the target of Leech Seed is also under the effect of (or was under that effect and healed itself with ), because Leech Seed and Toxic both use the same damage algorithm, Leech Seed damage will be affected by Toxic's N parameter, and will increase each turn.

In the Pokémon Stadium series, Leech Seed will not work against a target with a substitute.