► Playlist with other bosses: • [GBA] Mario & Luigi - ...
Weird video to have over 500k views, but ok.
Final boss(es): Bowletta - 00:58 / Cackletta Soul - 05:13
Not much I can do about the quality, though. It's an old video, so bear with me.
The freaking final battle at long last. Bowletta's battle theme is awesome and unlike all comical musics around the game this one is dead serious.
Cackletta's Soul right hand is weak against fire while the left is weak against thunder and its head is weak against fire. In the laser attack the right eye will fire against Mario, the left against Luigi.