I have a client that i wish to invest my time, photography, videography, video editing and graphic design capabilities into because he cant afford me. He is a pro boxer but hasn't had a fight yet, but he definitely has the skills to pay the bills. I'm not sure how I am supposed to get paid or what type of contract do I need?
Really, you don't need a contract for this case. Do the work for yourself personally and maintain all images and video as copyright to yourself. Just get a model release from him and then license back the works to him as you see fit.
By default, in almost all cases, the rights to creative content go to the content creator, not the subject. So unless you are actually selling stuff to him or are working as his employee, you own what you shoot and edit. He has no right to it other than what you allow him to have.
If you want, you could look at a long term contract for providing services for him related to future winnings, but that's really going to go beyond the basics of contract topics we can handle on a free online Q/A site as it then becomes more lawyer and jurisdiction territory.
Always create a contract and get a percent of the whole amount as an upfront payment.
This will always and always happen: people come to you to work with them and promise to pay later.
In reality what they want is: you invest your time, money and equipment and take a financial risk. You are free to do that, but then clarify to yourself that this is what you want to do: to be a financial investor.
Almost without exception those guys who can't get money to invest in your services will not complete the project and will not pay you.
I suggest that you separate your concerns. If you want to be a professional photographer or film maker or whatever, focus on that, and explicitly avoid investing your money and time.
If you want to be a financial investor and want to worry about your money, invest your money in it.
If you want to go the professional artist way, then you create a contract that gives you enough security that you will get paid. Clarify also the exact deliverables. This way the rules are clear, there is no way to get upset about misunderstandings, you are financially covered, and can focus on what you should be doing: creating great and artistic products.