The Pokédex in *Pocket Monsters: Diamond & Pearl* is a handheld electronic encyclopedia cataloging Sinnoh region Pokémon. It automatically records species data upon encountering or capturing Pokémon, displaying entries with names, images, categories, footprints, types, height, weight, and descriptive details—though full registration requires capture via catching, evolving, breeding, gifting, or trading. Featuring a dual-screen design mirroring the Nintendo DS hardware, its casing color shifts based on the Trainer’s gender: red for males, pink for females. Anime depictions show Dawn wielding a pink model and her rival Paul a black variant. Entries default to regional Sinnoh order but allow alphabetical sorting, with search filters for type, name initials, and body shape. Professor Rowan distributes this device to new Trainers. His assistant—either Lucas or Dawn, depending on the player’s choice—demonstrates its functions, including Pokémon capture protocols and operating the Dowsing Machine (later renamed Itemfinder). Throughout the storyline, the assistant leverages the Pokédex to thwart Team Galactic, partnering with the player in cooperative battles against the group. The Pokédex remains purely functional across all media, devoid of personality, character development, or autonomy. It lacks sentient traits or evolving roles beyond its programmed utility and excludes Rotom integration seen in later regions.