Works differently for Ghost-types.
Curse is a unique Ghost-type status move with a dual effect. When used by a Ghost-type Pokémon, it sacrifices half of the user's maximum HP to place a curse on the target. This curse causes the afflicted Pokémon to lose 1/4 of its maximum HP at the end of each turn. Conversely, if a non-Ghost-type Pokémon uses Curse, it raises the user's Attack and Defense stats by one stage each, providing a significant boost to its physical capabilities. In Polished Crystal, Curse can be learned by various Ghost-type and non-Ghost-type Pokémon, making it a versatile move that can either debilitate opponents or enhance the user's own stats depending on the situation.