Pokéradar
The 
Pokéradar is an item used for Shiny hunting. It records a chain of a Pokémon of the same species that you have hatched in a row.
Getting the Pokéradar
You can buy the Pokéradar in the shop, at the cost of 150.000 Pokédollars or 5 
nuggets.
Using the Pokéradar
How to access
You can access to your Pokéradar hovering over the Home tab located at the top of every page.
How it works
To create a Pokéradar chain, turn it on and hatch the same kind of egg repeated times in a row to increase the chances of hatching a Shiny. The maximum chance is of hatching a Shiny is reached after hatching 40 eggs. This chain resets if you hatch a different Pokémon.
Multiple forms are affected to this. For example, if you are hunting Shellos (West) and you hatch a Shellos (East), it will count as a different Pokémon and the chain will reset.
Note: Only eggs obtained from the Lab or Daycare will count for your chain, so eggs obtained through other means will not reset your chain if you hatch them.
That said, the Pokéradar presents some differences depending if you are a normal or premium user.
Differences between Normal and Premium Users
Normal users
- The maximum chance of hatching a Shiny is 1.25%. (1 out of 80)
- The battery is quite unstable for this radar; the Pokéradar will be out of charge once you hatch a Shiny or if you reset your chain. You need to buy new batteries with either Pokédollars, Electric Gems or Nuggets. The chain will start from 0 again.
Premium users
- The maximum chance of hatching a Shiny is 2.5%. (1 out of 40)
- The battery has unlimited power, meaning that the chain will not reset when hatching a Shiny and the battery doesn't have to be recharged again.
Notes
You can still hatch a Shiny without using a Pokéradar, but this chance is very slow so you will need a lot of luck. (This chance is slightly increased if you are a Premium member)
The Pokéradar doesn't guarantee that you will hatch a Shiny. Although you'll need a lot of bad luck for not hatching a Shiny after a long chain.