The NY Mets in their first season. It was about 120. It was in the early 60's
All MLB teams playing in 2012 have lost 100+ games in a season at least once except for the Angels who entered MLB in 1961. Their most losses in a season is 95 in 1968 and 1980. The Dodgers have not lost 100+ games in a season since 1908 when they played in Brooklyn and were known as the Superbas. The Cardinals have not lost 100+ games in a season since 1908. The Yankees have not lost 100+ games in a season since 1912 when they were known as the Highlanders. The Giants have lost 100 games in a season once, that being in 1985.
The single season record for most games lost by a Major League team is 134 games by the 1899 Cleveland Spiders. They only won 20 games in the 154 game regular season. The modern day record was set by the 2003 Detroit Tigers when they lost 119 games. They finished with a 43-119 record in a 162 game season. They had a 23-58 home record, and went 20-61 on the road.
The San Jose Sharks lost an NHL record 71 games in the 1992-93 season. The Ottawa Senators lost the second highest number of games at 70 during the same season.
As of the end of the 2007 season the Philadelphia Phillies have lost 10,028 games, the most in MLB history.
The Philadelphia Phillies
103 by the 1962 and 1966 Cubs.
The New Jersey Nets
The 1998 Yankees won the most regular season games. The Yankees won 125 games in 1998. 114 games in the regular season and 11 more in the postseason.