What if Pinky was smarter than the Brain, pretending to be stupid so he could thwart his plans for world domination every day thus saving the world?

He's the great unthanked hero, staying in character as an idiot day in, day out, keeping Brain out of trouble. Brain never suspected, never got to the point where he decided to remove Pinky from the picture.

Clearly the scientists had given super intelligence to both mice not just one.