What match problem are you trying to reproduce? You are currently seeing a breakdown in team cooperation because your dominant player doesn't need to pass to be successful. To fix this, stick with your 4v4 but add a 'goals must be assisted' constraint—meaning a goal only counts if at least two players on the scoring team have touched the ball in the build-up. Alternatively, designate one of his teammates as a 'target player' who must touch the ball before a goal can be scored. This forces the dominant player to scan for teammates and use them as decoys rather than just outlets. Observe whether he starts to recognize space elsewhere or if he still tries to do everything solo. If the game remains congested, keep the format, but adjust the pitch shape to be longer and narrower, which naturally discourages solo dribbling into heavy traffic.
