Our organization is loooking at adding a couple of Postgres and MySQL databases to our existing Oracle farm. I have found information indicating the Oracle OEM 12c can be used to monitor MySQL but from everything I have found there is not a plugin for use with Postgres.
Is it possible to monitor Postgres databases via Oracle EOM 12c?
MySQL can be monitored by using a plugin: http://www.pythian.com/blog/mysql-plugin-for-oracle-enterprise-manager/
Postgres can be monitored by using a plugin but I do not know about a existing plugin for Postgres. An option would be to create one yourself.