Agile project management - in brief: Agile - has become a common panaceum for all sorts of project management issues. Mostly chosen out of frustration with previous formal methods, it is told to make projects cheaper, more flexible and enhance motivation of project teams. Like it is the case with every wonder pill, it can be extremely helpful when used in the right context and by the right people. The other extreme, Waterfall project management, is designed to be used for series production, when a team creates a template which is the used thousands of thousand times in exactly the same way, like installing an operation system, update security policies in large scale or release a new version of a complex software component. Agile is the natural method of choice for prototyping and research projects, when the team creates a bespoke solution for a certain use case. For the wide majority of software projects and for nearly any ERP implementation it is Agile the method to use.
You do not need an agile coach or a certified Scrum master for Agile project management. The secret is not he method specification in detail but rather the fact that every team members practices all relevant day to day tasks together to work in harmony. You can learn this from every team sports like soccer or basketball, or when working in a larger kitchen that prepares a menu and a la carte dishes for hundreds of guests at the same time.
Like for any other project management team: it is important that every team member is trained in the project management in use, be it Agile or Prince-2 or PMBOK, V-Model, Waterfall or CHAOS. Compare again with sports: you cannot win a game if only the coach has learned to kick the ball: it is the players who need to understand the rules, guidelines and tactic.