We discussed monitoring Oracle Database with vRTVS a couple years ago, but there is another way to monitor as well, Telegraf! Here's how you do it.
Go to Environment - Applications - Manage Telegraf Agents and install the Telegraf Agent on the VM/s running Oracle Database.
Once installed, the Telegraf Agent will discover Oracle at which point we can configure the Telegraf Agent.
Once configured you'll see details, hundreds of metrics again the Oracle Database Instance, Event Wait Groups, and Queries.
Documentation on Telegraf Agent configuration for Oracle Database and more can be found here, enjoy!