Does the experience that my in-battle Pokemon receive get reduced if I turn it on? Thanks.
No, the in-battle Pokemon you send out gets all the experience, while the rest of your team gets half.
Source- https://bulbapedia.bulbagarden.net/wiki/Exp._Share
pokemon who enters the battle get full exp points and the ones sitting in the back gets half of the exp
The Pokémon battling gets its usual experience, but the party members get half of the possible experience.