Grass Pledge is a move introduced in Generation V that is only learned by a Move Tutor. The user attacks with a pillar of grass. When combined with Water Pledge the power of this move increases, and the land surrounding the opposing Pokémon becomes a moor. This effect reduces the opposing Pokémon's Speed Statistic by one stage.
If Grass Pledge is combined with Fire Pledge, the opposing Pokémon get surrounded by a sea of flames, which damages the opposing Pokémon by 1/8th of the maximum HP.