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