Overgrow (ability)

Overgrow is an ability introduced in Generation III. So far, 7 Pokémon have this ability. All Grass-type Starter Pokémon have this Ability, although it's not exclusive to them, and all Pokémon that have this Ability are Grass types. There are 3 variations of this Ability: Blaze, which affects Fire-type Attacks, Torrent for Water-type Attacks and Swarm for Bug-type Attacks.

In battle
Overgrow increases the power of Grass-type moves by 50% (1.5×) when the bearer's HP falls below a third of its maximum. (known in-game as "in a pinch")

Outside of battle
Overgrow has no effect outside of battle.

Trivia

 * Between Overgrow and its 3 variations, Swarm is the only one that no Starter Pokémon have.
 * Also, Swarm has the most Pokémon with this Ability, with 12, while Torrent has the least, with only 4.