Celtics have won 17 championships, and Lakers 16 - the two teams with the most championships. So yes, in many ways they are the most successful franchises in the NBA.
There are only 30 MLB teams in the MLB, but there are many places with a minor league park, but there are a few cities like Chicago and Los Angels that have two MLB teams. There are many cities without any teams.
Lakers & Celtics
Alabama does!
Pittsburgh is the NFL that has the record of two repeat championships in the NFL. There are six other teams that have own a repeat championship once.
They have a playoff
the wild card teams play the best team in each of the leagues
Deon sanders NFL super bowl and MLB
There are several teams each with two cars, Ferarri, Maclareans, Saubers, Renaults, B.M.W, Force of India and so on.
Both the Celtics and the Lakers combine to make up 33 championships between the two of them. Also they have some of the most historic players that played on both teams.
Boston Celtics
Two, the St. Louis Cardinals and the Kansas City Royals.