Hello ManPreet,
As you will register your plugin on the Plan Class Table,
1. You will get the GUID of the Plan Class Table record.
2. Now Just create a query on the "Class Requirement Table" just like below.
select Class Requirement table
where Plan class Table Record guid = from step 1.

Download this Fetch XML.
3. Fetch XML will look like below.
and that is how you will get the data.
4. Replace GUID with the Dynamic GUID when your plugin will run.

Thank you,
Amit Katariya