When a Pokemon with Primordial Sea enters the battle or a Pokemon gains the Ability Primordial Sea, the Ability creates heavy rain, a unique variation of rain. The heavy rain lasts as long as the Pokemon with Primordial Sea is in battle with the Ability. In a Rotation Battle, Primordial Sea will not activate if the Pokemon is sent out in a rotated-out position and will not activate if the Pokemon is rotated in; heavy rain will dissipate if the Pokemon is rotated out.
Along with the usual effects of rain, heavy rain causes damage-dealing Fire type moves to fail. Additionally, heavy rain causes the weather modifying moves Sunny Day, Rain Dance, Hail and Sandstorm to fail if used; and it causes the Abilities Drought, Drizzle, Sand Stream and Snow Warning to fail to activate.
If Primordial Sea is suppressed or replaced, the heavy rain it causes will disappear. If another Pokemon in battle has the Ability Desolate Land or Delta Stream, the dominant weather conditions will be determined by whichever Ability activated last.
Outside of battle
Pokemon with Primordial Sea