The user hurls up its stomach acids on the foe. The fluid eliminates the effect of the foe's ability.
This move disables the target's ability and it shall be ignored unless it is switched out. It cannot disable abilities that take place outside of the battle, nor abilities that have effect at the start of the battle because it would be activated before Gastro Acid was used.
Even though it is a Poison-type move, Steel-type Pokémon are still affected by it.
There are benefits of using Gastro Acid on an ally with negative abilities such as Truant and Defeatist.