Poké Radar appears in 10 version groups since Generation IV, a Gameplay item in the Key Items pocket
PokéAPI item 408 of 2,223, Gameplay category, Key Items pocket
Effect, in PokéAPI's words
Poké Radar: “Use to track down rare or shiny Pokémon. 50 steps to recharge.”
Designates several nearby patches of grass as containing Pokémon, some of which may be special radar-only Pokémon. Successive uses in a certain way create chains of encounters with the same species; longer chains increase the chance that a shiny Pokémon of that species will appear.
Games
Poké Radar is listed in the text of 10 version groups, first in Generation IV
Game index by generation
IIIIIIIVVVIVIIVIIIIX
Named in
Diamond and PearlPlatinumHeartGold and SoulSilverBlack and WhiteBlack 2 and White 2X and YSun and MoonUltra Sun and Ultra MoonLet's Go Pikachu and Let's Go EeveeSword and Shield