The Map Theme. Simple, but catchy. As the player defeats more bosses, the music gradually becomes more elaborate and awesome, adding instruments like strings and drums. This dubstep remix of the map theme counts as well.
The opening cutscene theme strikes an emotional chord with some gamers with its soft, music box lullaby sound. One can almost imagine the Mario Bros.' future parents playing it before they go to bed as they await the delivery of their children (the fact that the melody slows to a stop and has to be rewound midway through only adds to this).
Yoshi Touch & Go
For a simple tech demo, this game has some really good music. This remix of Flower Garden is the most well-known theme.
The beautiful and relaxing Sky Area theme plays when you're controlling Baby Mario.
The title screen music for the game starts off with typical beach sounds and after a while plays a soothing melody of the game's theme that plays during certain levels while giving a relaxed tropical feel.
Yoshi's New Island
Kamek's boss theme starts out similarly to the classic Hammer Bros. theme but then launches into a quirky, energetic, yet slightly sinister tune that fits the Magikoopa perfectly.