Related to this question (Can a sub-panel have a larger main breaker than the feeder breaker in the main panel?) on having a larger "main" breaker in a subpanel than in the panel feeding it, my question is similar, but has to do with a subpanel "main" breaker larger than the busbar ampacity/panel rating.
In this case, I have a subpanel (no ground/neutral bond) with a 200A panel rating and a 200A breaker in the panel feeding it. Can I install a 225A "main" breaker in the subpanel to act as a shutoff switch for that subpanel or is that prohibited by code since its rating exceeds the rating for the downstream busbar?