Yeah, I can't speak to the behind-the-scenes drama, but I agree that Pierce was at his best in Season One, where he was a little bit grandiose and a little bit of a jerk but still had moments of wisdom and humanity. I always liked the talk he gave Jeff in the boating episode.
Turning him into a total buffoon villain from season 2 onwards was a change for the worse.
Everett is at least a minor toon force user, so normal power scaling doesn't apply. He can beat anyone or be beaten by anyone depending on which is funnier.
Mrs. True can usually overpower him because he's usually being a jerk to her, but when she's in the wrong she's usually cowed by him.