In Montreal - hockey is far ahead of anything else. With the exception of the Covid era, the Bell Centre has “sold out” (i.e. all seats were sold, but not necessarily filled) every game for the last 20 years or so.
The football Alouettes, and MLS team sell out regularly as long as the teams are winning.
Moving up fast is women’s hockey, which started its current incarnation last season - selling out most games in a 5,000 and a 10,000 seat arena. I don’t know if they have enough support to sell out the Bell Centre continually (they did sell out one last year).
Basketball - one (semi?) pro team plays in a 5,000 seat arena and averaged about 3,500 last year. Basketball sells out larger arenas only when an exhibition NBA game is on (maybe one a year), or the Harlem Globetrotters are in town.
Baseball - there’s nothing at the moment - except amateur games.