Pokepedia
Generation IV Ability

Slow Start

Effect, usage, and Pokémon with this ability.

Slow Start is a Pokémon ability introduced in Generation IV. Halves Attack and Speed for five turns upon entering battle.

Full effect

This Pokémon's Attack and Speed are halved for five turns upon entering battle. This ability also takes effect when acquired during battle. If this Pokémon loses its ability before the five turns are up, its Attack and Speed return to normal; if it then regains this ability without leaving battle, its Attack and Speed are halved again, but the counter keeps counting from where it was.

For five turns, the Pokémon's Attack and Speed stats are halved.

Pokémon with Slow Start

2 Pokémon
Regular ability (1)
Hidden ability (1)