Ostinato

OstinatoDefault DataSpecial Attacks

Default Weather Condition-Inducing Attacks

The following attacks generate Weather Conditions for five turns, just like in Pokémon games. As you can see, it costs 5 VP to produce a weather effect for 5 turns, so if a character wants a longer-lasting ability, just make it cost 1 VP per turn (but it should be 2 for Underwater, Space, Superstorm, Asteroids, or Meteor/Comet Shower, since those are crazier). Or you could make it a spell and have it cost MP. Underwater and Space can only be removed as conditions if they were originally generated by an ability, and not if they are the larger setting—although it could be interesting to allow a move like Air Lock to generate a temporary air bubble around the battle, and have the weather return to Underwater or Space when it ends.

I would generally consider Air Horn to be a psychic attack (since it generates a Weather Condition that specifically affects psychic attacks), and it would therefore go in the psychic attacks section of a character's attack list, and would be disabled by Psych Out. But it's also fine to have a non-psychic version of it.