A champion is the person inside a prospect's company who wants your solution and advocates for it internally. They have influence but usually not final authority. A deal without a champion rarely survives internal scrutiny, because someone must argue for it when you are not in the room.
Most of your deal is sold when you are not there. Your champion is the one making the case internally, and they are doing it with whatever you gave them. If that is a generic deck and a price, they will lose. Arming a champion with the business case, in the language their CFO uses, is often what actually closes the deal.
Example:
A champion must justify the spend to a CFO. If all you gave them is a list of services, they cannot make the argument. If you gave them a payback calculation, they can.
How do you identify a real champion?
A real champion takes action on your behalf without being asked, such as arranging internal meetings or pushing the process forward. Enthusiasm without action is interest, not championship.
What does a champion need from you?
The business case in the language their decision-makers use, the answers to internal objections, and the confidence that advocating for you will not damage their credibility.