The Devon Scope allows the player to detect invisible Pokémon. This allows them to battle hidden Kecleon throughout Routes119 and 120, and grants them access beyond the northern bridge on Route 120 and enter Fortree Gym.
The Devon Scope provides the same functions as in the original games, but two extra Kecleon will appear after completing two major story arcs. After dealing with GroudonOR/KyogreAS, the player can uncover a Kecleon in the ladies' hot springs in Lavaridge Town. After completing the Delta Episode, they can find another Kecleon behind the astronaut face board inside the Mossdeep Space Center. The latter Kecleon has its Hidden Ability, Protean.
The Devon Scope appears in the Kecleon bonus stage of Pokémon Pinball: Ruby & Sapphire. It can be knocked down from the tree to make the otherwise invisible Kecleon visible for a short time.