Delta Stream is an Ability that was introduced in the Generation VI games Omega Ruby and Alpha Sapphire. This Ability is exclusive to Mega Rayquaza, and introduces a new Weather Condition to the series.
After becoming Mega Rayquaza, mysterious strong winds will kick up on the battlefield. Other weather conditions cannot be activated by another Pokémon's moves or Abilities, and all other weather conditions are overridden, including Primordial Sea and Desolate Land, which cannot be removed otherwise.
Only another Pokémon's Primordial Sea or Desolate Land can override mysterious strong winds once it is sent out in the field.
The effectiveness of moves that would be Super-Effective on pure Flying-Type Pokémon are also removed. This weather condition will persist until no other Pokémon with Delta Stream is in the field.
Delta Stream doesn't have an effect in the Overworld.
Pokémon With This Ability