Sap Sipper (Ability)

Sap Sipper is an ability typically found in Grass type animals. However, there are some exceptions.

In Battle Use
Animals with the Sap Sipper ability nullify any oncoming Grass type moves and raise the attack stat of the animals with the ability.

Speculation
This ability likely evolved from herbivorous animals that constantly fed on plants to give them Grass type features or benefits.