A recent Pokémon GO leak reveals that a new feature is in the making with respect to Raid Battles. According to the popular Pokémon GO data mining group PokeMiners, the new feature will be the move modifiers, which will take the raids to a whole new level.
When a Boss Pokémon takes over a Gym, Raid Battles occur. Your objective is to defeat this formidable Pokémon. If you and your teammates are successful, you will be rewarded with special items as well as a chance to catch that Pokémon. You can't do it alone; you'll need the assistance of other Trainers to raid the Gym and win.
Another interesting feature mentioned is the Shadow Raids in Pokémon GO. They appear to be exactly what the name suggests: Raid Battles with powerful Shadow Pokémon bosses. Shadow Raids, like normal raids, will have five levels. Shadow Raids in Pokemon GO, on the other hand, appear to be accessible via a raid ticket according to the leaks.
The miners have additionally revealed that a few more inventory items were added to the main battle action section of the code. Also with that, Raids can now reward specific XL Candy that can be fed for specific Pokemon. Usually, mining leaks are true and hopefully, this will be reflected in the game soon.