Whether it is code compliant or not (I believe it most likely would be if the panel is listed for that breaker), I imagine it will be very difficult to pull off. You will lose 4 spaces in the panel and need to route some large, stiff, expensive cables through the panel, the wall and to wherever the sub is going to be mounted. I would take a long, careful look at whether I really needed a 200A feeder to the sub-panel.
I ran a full load simulation on my house not long ago. With everything I could reasonably get running, including all lights, 7.5 HP compressor, electric oven, dryer and 2 HVAC units, it only pulled 60 Amps on a 150 Amp service. The only things not running at the time were my welder and 250W per channel audio amp. Based on that, I am satisfied I'm not going to run out of current any time soon even if I were sandblasting, welding, drying clothes and baking cookies simultaneously while cranking DSotM at 11.