Pokémon Brilliant Diamond and Shining Pearl brought back a ton of the features from the original gen-four titles Diamond and Pearl, but there have been some drastic changes to make things easier for players.
One of the biggest changes is how XP works while you’re adventuring. In the original games, you’d need to be using a Pokémon in the battle for it to gain XP and level up. Alternatively, you could give the Pokémon an EXP Share to hold, which would give it a small amount of XP for battling that other Pokémon in your party.
In Brilliant Diamond, Shining Pearl, the model that has become more apparent in recent games is adopted where XP is distributed across the entire party regardless of which Pokémon are used in battle.
This is extremely useful for new players and something that makes progressing in the game a ton easier than it originally was but for some people who are looking to reexperience the Sinnoh region as close as they can to how it was originally, this could cause issues.
Can you turn off EXP Share in Pokémon Brilliant Diamond, Shining Pearl?
Unfortunately for those players who don’t fancy this new system, there is currently no way to turn off the EXP sharing function. It is automatically active in the remakes.
Sadly, it wouldn’t be likely that the option is introduced post-launch so players are going to have to continue the game with this added feature live at all times.