Rattled

When a Pokémon with Rattled is hit by a Bug, Ghost or Dark type move, its Speed is raised one stage (up to the usual maximum of +6 stages).

Game descriptions

Black, White, Black 2, White 2:Some move types scare it and boost its Speed.
X, Y, O.Ruby, A.Sapphire:Some move types scare it and boost its Speed stat.
Sun, Moon, Ultra Sun, Ultra Moon:Dark-, Ghost-, and Bug-type moves scare the Pokémon and boost its Speed stat.
Sword, Shield, B.Diamond, S.Pearl:Dark-, Ghost-, and Bug-type moves scare the Pokémon and boost its Speed stat.
Scarlet, Violet:The Pokémon gets scared when hit by a Dark-, Ghost-, or Bug-type attack or if intimidated, which boosts its Speed stat.