The Dive Ball only works after using Dive in RSE (underwater), but it works under 3 circumstances in later games including ORAS: underwater, fishing, and surfing, according to this:
The Dive Ball is a PokéBall that works best on Pokémon when you are Underwater having used the HM move Dive in Ruby, Sapphire & Emerald. In later games, the Dive Ball is more effective on Pokémon who are found in the water while Surfing or Fishing. When Underwater, Surfing or Fishing, the Capture Rate of the Dive Ball is 3.5. At all other times, it is 1.
“Later games” would refer to ORAS, since RSE is the only one mentioned that only works with being underwater.
Secondly, as shown here and also here, Dive can only be used to access the Abyssal Ruins in all Gen V games, which have no Pokémon in them.
Hope I helped!