Theatrhythm Final Fantasy has 4 player Co-op Mode.

[blkfish92]

MrT-Tar said:

For battle themes: I heard One Winged Angel, Dancing Mad (part IV), 4 Elemental fiends battle theme, FFIII boss theme, Man with the Machine gun, Clash on the Big Bridge, FFVI decisive battle amongst others.  

If the game has the following then it is a must buy:

My cousin is obssesed with this boss theme LOLOL