Back in the 70s there was a fad started by a book called “New Games.” It was all about noncompetitive play. For example, the “Tug of Peace” game, which is just like Tug of War, except that when one team starts losing, kids on the end of the “winning” side let go and run to join the other side, the object being to have everyone pulling as hard as they can, with the whole mess perfectly balanced. I don’t know if those books still exist, but it might be a way to teach him to channel some of the competitive energy into cooperative energy. Just a thought!