Screech will lower the opponent's Defense by 2 steps (termed BTLs in the Gameboy description) on the Stat growth scale.
Screech will always fail if it has already been used 3 times on the same pokemon, without a move that raises Defense being used by or against the pokemon affected by Screech. This is due to the fact that a stat may only be lowered by a maximum of 6 steps, until it is reset by the use of Haze or the pokemon is switched out normally. The maximum is the limit of how many decreases can be applied to a stat. If another move decreases the Defense stat of the pokemon that Screech is used against, the number of steps that it decreases the Defense stat by will count toward the 6 step limit. This will not reduce the number of times that Screech can be used unless the decrease is by at least 2 steps. The decrease will still max at 6 steps, so Screech will only provide a 1 step decrease if there are already 5 steps of decrease in effect.
Screech is affected by Brightpowder when the opposing pokémon is equipped with it.
Like all other non-damaging Normal-type attacks, Screech affects Ghost-type pokémon, despite their immunity to Normal attacks.
