Nintendo Life reports:
The base application, which costs 170 Yen, is similar to the pre-installed 3DS app Pokédex 3D, giving information on each 'mon as well as displaying an accompanying 3D model. It will only include information on Pokémon found in the Unova region at first, but once the app has been downloaded Pokémon from the Kanto, Johto, Hoenn and Sinnoh regions can be added for 500 Yen each using in-app purchases, so for a full 'dex you'll need 2170 Yen...
The app comes from The Pokemon Company, so before you get all excited that Nintendo is making apps for iPhones, take note of that.
Actually you'll have to wait for the Miiverse app before you can say that Nintendo has made something for iOS.