To carry over your Pokémon Sleep data from one device to another, you need to link your accounts. To find out how you can do so for this sleep tracking mobile application, you can check out this guide from Seeking Tech.
1. To begin, open the Pokémon Sleep App, log into your account and then skip past any dialogue until you get to the main screen.
2. Next, you need to tap the Main Menu option located at the bottom.
3. From the Main Menu, select the Settings and More option located on the bottom right side.
4. You should then tap the Link Accounts option from the Settings and More menu.
5. In the Link Accounts screen, you should see the following description:
By linking accounts, you will be able to carry over your play data if you change devices.
To link your Google account with your Pokémon Sleep account, select the Sign in with Google option and then log into your Google account.
To link your Facebook account with your Pokémon Sleep account, select the Log in with Facebook option and then log into your Facebook account.
If you don’t have a Google or Facebook account but would like to transfer your Pokémon Sleep account to another device, then you can select the Check Transfer Code option. You can then input the Support ID and Transfer Code on the other device to transfer your data.