Teams and solopreneurs in this program must be ready to spend several hours per week working on their project over the 6 weeks of the program.
A good I-Corps mentor is first of all someone you get along with and can work with for 6 weeks on your project! Then, you should be looking for an individual with professional experience in industry or startups who is willing to spend 1-2 hours per week helping you. It is even better if that person knows the industry you will likely be entering (but this is not material for your success in the program).
Remember, mentors are there to support you and help you ask yourself good questions. They are usually busy individuals so use their time wisely. Conversely, please engage them as they have a lot to give.