Fuel cell system lifetime represents a crucial factor for the successful use in automotive applications. To extend the system´s lifetime, realistic tests during the developing process are vital. Fuel cell systems are typically controlled with their balance of plant (BoP) components. In order to perform highly dynamic tests (e.g., emulating automotive scenarios or stress tests), a sophisticated control strategy of the BoP components must ensure the desired gas conditioning at the fuel cell. Due to generally strong coupling in the gas conditions, conventional testbed control just allows for slow changes between operating points. In contrast, we introduce a strategy with the goal of conditioning the fuel cell as fast as possible. The advantages of the proposed strategy are: 1) Highly dynamic testing scenarios are precisely tracked; and 2) Desired gas conditions (fuel cell inlet pressure and flow) can be independently varied. The presented testbed control is beneficial to either induce or avoid detrimental conditions or to decouple the desired gas conditions for diagnosis tools (e.g., EPIS). To realize highly dynamic control, a model-based control approach using a nonlinear model is derived. The model is parametrized employing real testbed measurements. This strategy applies the framework of exact input-output linearization to decouple the desired gas conditions. Essentially, the proposed control strategy determines the BoP component setpoint trajectories to independently guide pressure and flow along desired dynamic trajectories. The control framework was successfully implemented at a real testbed. Controller performance was demonstrated for highly dynamic tests with a real working fuel cell.