Complex sentence: Gale of Darkness, the reverse engineered model used by the protagonist can identify Shadow Pokemon by itself, which also serves to prevent the machine from being used to snag normal Pokémon.
Split into simpler sentences: Gale of Darkness, the reverse engineered model used by the protagonist can identify Shadow Pokemon by itself. The device also serves as a failsafe which prevents the machine from being used to snag normal Pokémon.