I don't "want" to be nitpicky...but the post said city and all the other ones listed were in the city of Toronto....if you expand it to GTA...I think there would be a few. Clarkson GO has 1200 in its new garage, no? Doesn't Square One have a large parking garage? Bramalea City Centre has a large parking structure and a large underground in addition to its surface parking.
Pickering GO has a 1,700 car structure.
I think the parking garage under Maple Leaf square has ~1,200 spots. ~360 for public use and the balance for condos.
Oakville GO has about 1,400 in its parking structure.