● Calendar events
Events saved in Google Calendar can be shown on multiple devices: register the same Google Account on each device and turn on "Calendar Settings" → "Link Google Calendar".
Events in the "Local calendar" (the calendar stored on the device) are saved only on that device and are not synced to other devices automatically. Save events you want to see on other devices in a Google Calendar calendar.
● Syncing ToDo, note, and diary data
You can move this data to another device with "Google Drive backup". On the device with the latest data, tap "Create Backup" (or "Overwrite Backup" for subsequent backups). Then, on the device that should receive the data, tap "Restore From Backup" to apply the latest data.
Please note that this is not automatic syncing. You need to back up and restore manually each time.