Instead of making things overly complicated, it would be possible to make the Arena control the movements of each bot or use custom AI tactics that would make the bots play soccer rather than attack each other.
For the custom soccer arena: Depending on how many community members want to participate, I would be willing to write up some coding for the Arena to control the movement of AI bots. Doing things this way would result in less lag but it would be less accurate than separate AI.py files.
For the custom AI files: I have actually written up rules for a programming tournament that would require teams to make their own soccer playing AI. It could take place before a basic soccer tournament (that way, there would be several choices of AI.py files that would specialize in different things) or I could alter the programming tournament a little to include more community involvement (it already allows some non-programmer involvement). Another idea would be to make one AI tactic that could be used for all soccer bots made by the community.
If there is enough support for this, I would be willing to code/host anything necessary to get this thing off the ground.