Niantic have announced they will stop supporting Apple Watch devices, starting with 1 July 2019. There are a few features users may have liked on Apple watches but Niantic posted some workarounds to help with the device transition.
Once the support for Apple Watch ends, players will no longer be able to log into the game with these devices. On the other hand, there is nothing an Apple Watch could offer that a different mobile device couldn't.
The reason for this is Adventure Sync and this feature is the culprit behind the downfall for Apple Watch. Pokemon Go can be integrated with Apple Health or Google Fit, depending on whether the player uses an Android or an iOS device, respectively.
Adventure Sync also allows players to track their steps even when they are offline and reap the rewards upon logging in. This way, they can hatch eggs, get candy and more without having to be online all the time.
Niantic they wanted to focus on Adventure Sync going forward which will benefit the players as well since they will not need to use two devices in order to get the rewards. Players who may have some unclaimed rewards will have plenty of time to redeem them until 1 July 2019.
On top of that, Adventure Sync will continue tracking data from Apple Watch or any other fitness devices the players synchronised.
Just in case someone is not familiar with the quirks of Adventure Sync yet, it is possible to use the feature even when walking or running on a treadmill so keep your device on you while going for cardio in order to get the most out of it.
Some players have reported Pokemon Go Plus interfered with Adventure Sync, specifically when using distance tracking since it overrides Adventure Sync's data. On the other hand, having Pokemon Go Plus Plus could potentially be useful since tracking sleep shouldn't cause compatibility issues.