I have no idea how it works! how do I get it? what does it do?
Having taken a break from Black & White, the Poké Radar makes it's triumphant return in Pokémon X & Y. After you have defeated the Elite Four, if you go to 2F in Sycamore's laboratoryand speak to the scientist, he will give you the PokéRadar. Each day, he will give you a Pokémon to study and, if you return having done a chain of them, you will receive an item such as an Ultra Ball. The PokéRadar works largely the same as before. When you activate it, several areas of grass will shake. When you go to them, a Pokémon will appear. Defeat it and it will commence and continue a chain and more areas will shake. The more a patch of grass shakes, the rarer the Pokémon. If you continue the chain, there is a hidden bonus of the possibility of a shiny patch with the probability topping out at a chain of around 40. The general rule of thumb for continuing a chain is that the patch should be at least four squares away from you. If it's on an edge, the chain will end. If you get interrupted by other wild Pokémon, the chain will end. If you enter a patch with a different Pokémon, the chain will end. If you equip the rollerskates, the chain will end. If the patches you receive don't match the initial shake or are too close, you can reset this instance of the chain by walking on the grass to power the Radar and activating it again. Patches of grass as well as flower beds are all capable of being utilised for PokéRadar chains. ~Serebii
The Pokeradar is basically a device used to find where Pokémon are and hunt for shinies. Sorry for the long answer.
