The Seattle Mariners today are the 1969 Seattle Pilots. Of course, you can't honor the Seattle Pilots from any other year since that was their only year in existence as they moved to Milwaukee in 1970.
There have been a few other franchises that played one year in a city and then moved. There is one other team playing today that also played just one year in a city. And that would be the Baltimore Orioles who played their first season in the American League, 1901, as the Milwaukee Brewers, before moving to St. Louis.
Less celebrated would be the one-year wonder Indianapolis Hoosiers who won the Federal League pennant in 1914 and moved to Newark for the Federal League's final season in 1915.
An obscure American League team playing north of Philadelphia and south of Boston, played its first two seasons as the BaltimoreOrioles.