Minor League teams that play in the same city as their major league affiliate.

[TheFugitive]

Minor league franchises that are located in the same city as their big league parent
club is a phenomenon most often found in hockey.

The earliest example of this I can find is the AHL's Boston Braves, who were in existence from 1971 to 1974.
The Boston Bruins were a very hot commodity, coming off of back-to-back Stanley Cup championships.  Tickets to their games at the Boston Gardens were sold out way in advance.  The Bruins' owners, seeking to both take advantage of Boston's insatiable demand for hockey, and to cut travel expenses for players going back and forth, relocated their AHL farm team to play in the Gardens on days when the Bruins were not.

The Braves folded after the '74 season due to dwindling attendance.   The idea would lay dormant for another twenty years until the Philadelphia Flyers decided to relocate their AHL farm team to Philly for pretty much the same reasons.  In the case of the Flyers their AHL Philadelphia Phantoms franchise was able to have it's own arena, as the Spectrum, formerly home of the Flyers, still stood across the parking lot.   The Phantoms would play there until 2009 when the Spectrum was finally demolished to wake way for a casino and entertainment complex.  The Phantoms moved to upstate New York for a few years, before settling into a new arena in Allentown, PA, about an hour north of Philly.

Today in the NHL there are several teams who keep their top AHL farm team in the same city.  The Toronto Maple Leafs top affiliate, the Toronto Marlies, play in the Coca-Cola Coliseum, located on the grounds of the Canadian National Exposition.   The Manitoba Moose, top affiliate of the Winnipeg Jets, share the Bell MTS Centre with their parent club. Likewise the San Jose Barracuda share an arena with their big-league affiliate Sharks. 

The Laval Rocket, top farm team for the Montreal Canadiens, play in Laval, Quebec, 22 miles from Montreal.  That one is close enough that it likely counts too.  The Los Angeles Kings' top farm team plays in Ontario, California, 37 miles from the Staples Center.

Looking at baseball the only good example I could come up with was New York, where the Yankees have a class A team located on Staten Island, while the Mets affiliate in the same league plays in Brooklyn.

In the NBA the Nets, Knicks, Bulls, Grizzlies, Clippers, Lakers, Mavericks and Jazz all have local affiliates
in the developmental G League.

[TheFugitive]

oh, and the Raptors.  Their G-league team actually won that league's championship last season.

[TheFugitive]

Yesterday tuned across a hockey game on my dish that featured the Chicago Wolves.
They are an AHL franchise that plays in suburban Rosemont, Illinois.  Founded 25 years
ago, they are interesting in that they play in the same market as the NHL Chicago Black Hawks,
but they are not affiliated with that team in any way (they are actually the top farm team
for the Vegas Golden Knights).

Oddly enough the other team that they were playing was the Black Hawks top farm squad,
based in Rockford, Illinois, some 90 miles away.

[TheFugitive]

Caught a late-night online telecast of a game between the San Jose Barracuda
and the Tucson Roadrunners.

The game was played at the SAP Center in San Jose, where both the NHL Sharks
and AHL Barracuda play.  The official attendance was listed as 2391, but based on
visuals of the seating area I would be surprised if more than 250 people were actually
in the building.

This appears to be an experiment that is destined to fail.