Move Biztalk databases

First, as I think, this a SQL Server issue, moving the databases from a server to another

Second, as I think, you need to reconfigure your BizTalk group, and your BizTalk server so that they refer to the new SQL server instance.

Hope that this is helpful,

I think you should be able to do it by backing up your BizTalk databases (using the proper backup jobs, not the standard SQL Server facilities) and following the instructions in the documentation on how to restore them to a different computer and having your biztalk installation point to them. You can find those docs here: Restoring BizTalk Databases to Alternate Computers.

However, notice you'll need to have biztalk already configured using domain groups and accounts; if you have it configured with just local accounts, then that won't work, and you'll need to first unconfigure your biztalk (ConfigFramework.exe /u) and run configuration again to recreate your biztalk installation from scratch, using the proper accounts for a multi-machine installation.