Congress can block him only if he permits himself to be blocked by Congress.
Not exactly.
Congress can block him using Constitutional methods. They chose not to do this with Obama. They will choose to do so with Trump. The fact that they are complete hypocrites who didn’t exercise this power with Obama will never be mentioned except by Fox News, Hannity, Levin, Rush, here on FR etc...
The mainstream media will spend all day, every day, running Chuck Schumer, Colin Powell, and all the other big government types in front of the cameras talking about how Trump can’t do X and how Congress will stop him.
Mark my words - they will do EVERYTHING in their power to prevent him from succeeding on ANYTHING.