This answer addresses two separate questions:
Should list questions be allowed on Sports.SE?
In my opinion, list questions are okay as long as the list is not so big that the question is essentially meaningless. Here is an example of a good list question:
Olympic medalist in both the Summer and Winter Olympics
One of the reasons that this is a good question for SE is that it is a finite list. You can look at the history of the Olympics and figure out the answer. As time goes on and new athletes meet the criteria, this answer can be edited by someone to keep it current.
Here are a couple of examples of poor list questions, in my opinion:
Father and son who were active players at the same time? - The problem with this question is that it is too broad. The way it is written, the answer is practically infinite. Anyone can keep adding sports and athletes, at any level, and there is no way to verify any of it. I've written more about it on this meta answer.
NFL Tactical Knowledge - In addition to being an unlimited list question, it is primarily opinion based, as anyone could add a link to whatever football-related blog or Youtube video that they think is good.
Should the answers to list questions be made Community Wiki?
Community Wiki answers are for situations when multiple users contribute to an answer. The main purposes of Community Wiki answers are twofold:
They prevent someone from gaining rep from a good answer that they had little to do with writing. For example, if I answered a list question with one answer, then 5 more people added additional answers, adding to the list, and someone incorporated all of those answers into my answer, it might not be considered fair for me to gain all the upvotes for an answer that was essentially written by the community. Converting the answer to Community Wiki addresses this.
Community Wiki answers are easier for more users to edit. Keep in mind that any answer can be edited by anyone, but normally, the suggested edit for most users must be approved before it takes effect. On a Community Wiki answer, anyone that has 100 rep can edit the answer and have their changes take effect immediately. This might be useful for some answers to list questions that are going to need lots of edits to keep them current.
I think that whether or not an answer to a list question should be made Community Wiki depends on the individual question and answer. If the list is small, and the answer is primarily the work of one person, there is no need to make it Community Wiki. If the list is large and has lots of contributors, then a Community Wiki designation might be appropriate.
For some of the questions we are discussing, here is my opinion:
Father and son who were active players at the same time? - Community Wiki makes sense for this answer, because it is the work of many people, and new answers could come in from anyone at anytime.
Olympic medalist in both the Summer and Winter Olympics - In my opinion, a Community Wiki designation does not make sense here, because the answer is entirely the work of one person, and new answers will only be added at most every other year during the Olympics. If someone needs to be added to the list in the future, and I haven't done it, someone else can suggest the edit. If at some point a bunch of new answers are added that requires the accepted answer to be significantly altered, Community Wiki might be appropriate.
Which player had the longest professional career? - This is an interesting one: Is it a list question or not? The title of the question suggests not; there should only be one professional athlete with the longest career. However, the body of the question opens it up to a list of every single sport in the world. Community Wiki is fine here.
Any answer author can make their own answer Community Wiki at any time; I don't have a problem with that. However, I think that Moderators should be very careful turning an answer into Community Wiki. It should be a very rare occurrence. I certainly don't agree with searching the site for old list answers and changing them all to Community Wiki automatically. Community Wiki should only be forced on an answer in the cases where the Moderators think that rep has been awarded unfairly to a user and that so many edits are expected in the future that the normal suggested edit process would be too burdensome.