Is basic Splunk good enough for PCI DSS compliance or is ES or Splunk App a must have?

I am not too familiar with Splunk so Just trying to figure out if Splunk (with use cases set up of course) is good enough to meet PCI DSS 4.0 requirements or do we really need ES or Splunk App to meet the requirements?

Secondly, is it true that ES requires logs to be in CIM format whereas there is no such requirement for Splunk?

Can someone please clarify the above for me? Thank you, in advance.