There are lots of executive actions which require consent of congress. I think that would work fine here. Obviously, the point is for congress to have a means of overriding a corrupt pardon (not that such a thing would ever happen!)

The benefit of vesting a power in the executive is unity of purpose (regardless of what administration is in power).

The benefit of Congress is slowing and deliberating over knee-jerk decisions.

Having the President initiate and Congress approve plays to the strengths of both offices.