Physical versions of a game can be shared between any Nintendo Switch as long as you insert the game cartridge. 

If your Nintendo account is linked to your Ubisoft account, you will also be able to share any additional content attached to your Nintendo account. 

Digital versions of a game, and any additional content, can be shared between any Nintendo Switch, as long as your Nintendo account is linked to your Ubisoft account. You will then be able to share any Ubisoft games or additional content attached to your Nintendo account. 

For more information about the Nintendo account management, please get in touch with Nintendo support. Their teams will be able to help you with issues relating to Nintendo Switch.