I have initiated a proof of concept with Arduino Micro and BLE of Adafruit, you can find it in the repository of the project

https://github.com/sabas1080/PokemonGODIY

I have used the library BLE Peripheral of Sandeep Mistry

https://github.com/sandeepmistry/arduino-BLEPeripheral (available in Manage Library of Arduino)

Also I have used the Arduino Micro because Arduino UNO have low memory for this project, for the moment I 've only added services and characteristic of Pokemon Go Plus.

Welcome you help and comments