The Pokémon GO version being used in the ongoing field test was recently updated, adding a few new features to the app, including the ability to train at gyms. [Thanks, Nintendo Everything.]
Additionally, information leaked from the test indicates that Pokémon GO features real-time combat as opposed to the turn-based battles found in the series.
Here is some more information from reddit on the updated field test:
Pokemon GO is scheduled to release sometime this year for iOS and Android devices.