PS! Chrome Sync is a free Chrome add-on developed by psgcsync. It allows users to sync their Pokemon Showdown teams across different instances of Google Chrome. With this add-on, you can save your teams in your Google Account's sync storage and access them wherever you use Chrome.

The add-on periodically saves Pokemon Showdown's local storage to Chrome's sync storage, ensuring that your team list is always up to date whenever you load PS!. This means that any changes you make to your teams on one device will be reflected on all devices where you use Chrome.

Please note that on the first use, the extension will save all of your teams to the Chrome sync storage. This may result in the initial loss of any teams stored locally on other devices. However, once the sync process is complete, all devices will be kept synced, providing a seamless experience for managing your Pokemon Showdown teams across different devices.