Which CFL teams have never met in grey cup game?

Answer 1

Because the Grey Cup game is played between the Western Champion and the Eastern Champion, West-west matchups and East-east matchups do not happen as a rule.

The exception is the Winnipeg Blue Bombers who have played both in the east and in the west, and have played all of the other teams at one time or another except Montréal. (Toronto most recently in 1950, Hamilton most recently in 1984, BC most recently in 2011, Sask in 2007, Calgary in 2001, Edmonton in 1993)

So, Hamilton, Toronto and Montréal have never played each other (unless you count the 1912 Hamilton-Toronto game, but that was a different Hamilton team). Likewise, BC, Calgary, Edmonton and Saskatchewan have never played each other.