The Iron Wall Badge is new for NBA 2K20 and is a Rep Reward for achieving Pro 2 Status. This badge allows your player to set harder screens than even Hall of Fame Brick Wall allows.
Iron Wall is one of the most effective badges in the Park once unlocked, as it allows bigger players to set screens that knock smaller defenders down and completely shut down bigger players. Take a look:
Iron Wall still triggers randomly, so we recommend having a higher Brick Wall badge level as well. The two badges go hand-in-hand, but Iron Wall only amplifies the effect of Brick Wall, not replace it.