The Oshawa Majors were at first a junior team.
In the 1934-35 OHA Junior A Season the Majors made it to the provincial final. In that series it was discovered that one of their players, Bill Bagnall. was overage. Their opponents, the Kitchener Greenshirts, agreed to continue playing the final on the understanding that it was only to qualify for a spot in the 1934-35 Eastern Canada Memorial Cup Playoffs. There was a tight deadline for that. Later on the championship would be decided in another playoff. The Ontario Hockey Association (OHA) agreed.
The Majors, without Bagnall, won this series and lost out to the Sudbury Cub Wolves in the 1934-35 Eastern Canada Memorial Cup Playoffs. Meanwhile, the teams that had lost to the Majors in the OHA playoffs - Toronto Lions, Toronto Young Rangers, & Kitchener Greenshirts- played off for the right to play the Majors for the OHA championship. The Greenshirts won these playoffs.
The Majors, however, refused to replay the Greenshirts. They said that the original final was for both the Eastern Canada playoff spot and the OHA championship. The OHA disagreed and awarded the championship to the Kitchener Greenshirts.
In the 1935-36 OHA Junior A Season, the Majors were in a group on their own. They lost the provincial semi final.
There was a Majors team in the 1960-61 OHA Intermediate A Playoffs. They lost the provincial final.