It sounds like you already know that you can customize a Transaction Report to contain only Income categories. But the problem is having to go through and identify which ones to turn off and which ones to keep enabled? But does it matter? If you generate a Transaction Report with all categories, the top level sections are Income and Expense. You can collapse the Expense section so you are only seeing the Income part.
It looks like you're new here. If you want to get involved, click one of these buttons!