Leaders must explain the behaviors expected of the teams and encourage the Scrum Masters, Product Owners and Developers to watch out for these dysfunctional behaviors. Everyone coaches everyone. What a leader can NOT do, is reprimand people who are not playing their roles correctly. The Scrum teams themselves must learn to self-align. If the leader takes this over, the hierarchy is back.
In every meeting and every conversation, leaders must reinforce the collaborative culture required for Agile repeatedly. Once is not enough. Most important, the leader must model Agile behavior by constantly pushing decision making to the team as a whole.