"Super Mushroom (Beta Mix) - Super Mario 64 DS" is a high quality rip of the beta mix of "Super Mushroom" from Super Mario 64 DS.
Joke[]
This is an arrangement of "ぽっぴっぽー (PoPiPo)" by Lamaze-P using the instruments of the advertised track, with the vocals of "ぽっぴっぽー (PoPiPo)" mashed up as well starting at 0:17.