A way to create databases, or are you talking about a way to automatically
catalog remote databases (including host databases)?

What platform?

On Windows, you could prepare a sample machine set up the way you want, then
use db2rspgn to generate a response file and companion files which can then
be used as a single group to reproduce that same setup on other machines.

On unix/linux, you could do largely the same thing using db2cfexp and
db2cfimp.  Export with db2cfexp the configuration of each instance, and
then, after your script has installed DB2 using a response file, use
db2cfimp to import the configuration, which includes cataloged nodes and
databases.

For databases, creating databases is a separate activity after installation
as that often requires tablespace setup that can be machine specific.