What are the Smart List and Flows required to obtain more information on recipients that produced a 'email invalid' response?
Please move the thread to Products (Move link will be at the right). This isn't a support space but is for discussing the Champs program itself.
Can you clarify what you're looking for when you say "more details"?
If you're just looking for the records who meet your criteria, not to commit any action on those people, you just need a smart list - not a smart campaign (which use smart list criteria and flows).
Creating a smart list with "email invalid = true" will give you a list of everyone with that value on that field. If you want a list of everyone who was marked invalid as the result of a specific send, then you likely want something like "data value changed, attribute is email invalid, new value is true, date of activity is (date of email send)". Depending on the send volume of your instance (if there were multiple campaigns sent on that date), you may also want to further constrain it with email/campaign specific criteria (e.g., "was sent X email", and "not was delivered X email").
You can use a smart list trigger of "Email Bounces" and capture more details into custom fields with a few trigger tokens: