Data serialization for multiplayer games

I am looking for guidance on what type of serialization to use for a multiplayer sports game. The game can have up to 8 players and will use TCP for server to client communication. I have never written a multiplayer game this complex, but I suppose that the clients and server will need to be constantly communicating this data:

- Location of players and game object (ball)
i) Vector3 for their transform
ii) Vector3 for their current velocity

So roughly this is up to 18 vector 3s, plus...

Data serialization for multiplayer games