All of the final boss fights in the New Super Mario Bros. Series played 2 player co-op except for New Super Mario Bros. DS. Here are the time stamps for each boss.\r
\r
00:01 - New Super Mario Bros. (DS) - Final Boss\r
01:21 - New Super Mario Bros. Wii - Final Boss (2 Player)\r
07:00 - New Super Mario Bros. 2 - Final Boss (2 Player)\r
12:00 - New Super Mario Bros. U - Final Boss (2 Player)\r
18:02 - New Super Luigi U - Final Boss (2 Player)