91.205 only addresses the minimum equipment required for any aircraft to be airworthy for flight.
Appendix 7 of the Private Pilot ACS refers to 61.45, Practical tests: Required aircraft and equipment. But that doesn't specifically address the question, it just says equipment necessary to demonstrate the required tasks. I assume your Ercoupe with rudder pedals would be capable of this, I'm not sure, though. For crosswind t/o and landing, the ACS just says proper control manipulation and directional control, which could be maintained even with the Ercoupe without separate rudder control. But, another question, can you Forward Slip an Ercoupe without the rudder control?
Probably the bottom line, if in doubt, ask the examiner which you intend to employ for your checkride.