With DB2 LUW (unlike DB2 z/OS) you do not need one table per tablespace. Tables should be assigned to tablespaces based on bufferpool configuration, since bufferpools are assigned to tablespaces. This applies if you have more than one bufferpool. Generally, it is good to put indexes in a different tablespace than data, so that you can have a different bufferpool for indexes.
You must have at least one system temporary tablespace, preferably SMS. This should have been created by default when the database was created. In some cases you may need a system temporary tablespace with a larger page size (32K) if a query returns a select list wider than your default page size and if DB2 needs to spool the result set to a system temporary tablespace.
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390