Bengals
The Bengals
No
They were the 6th ranked team in the nation before Brett Favre and the Southern Miss Golden Eagles beat them.
no
The Detroit Lions, 28-24, on January 8, 1994 in Favre's second season with the Packers.
New England Patriots
The day after Irvin Favre died Brett defeated the Oakland Raiders, 41-7 on Monday Night Football, December 22, 2003
Brett Favre
Yes, on Sunday, January 17, 2010.
Brett Favre was the winning quarterback of Super Bowl XXXI, played January 26, 1997, when the Green Bay Packers beat the New England Patriots 35-21 after the 1996 season. (Favre and the Packers lost Super Bowl XXXII to the Denver Broncos, 24-31.)
He is the only quarterback in the NFL to have beat every team, including the Cowboys. Yes, he has beaten them.
On October 17, 2010, Favre and the Minnesota Vikings defeated the Dallas Cowboys 24-21 in a game played at Minnesota.