When you get to the Final Boss Room, note the layout. See that extra space near the Throne where the arena narrows? Anytime a Player gets in that space, the Boss moves to one side of the nearest part of the wider section of the room and stays there until the Player leaves that space. (Probably because he can't turn around to fight you.)

Thus, have a Player go to the Throne and then the other Player can kick the snot out of the Boss from a diagonal while dodging the occasional kick from the boss instead of needing to chase the boss around. (You can have a second "Player" join mid-fight if you got here alone.) If you still end up getting low on time, remember that losing a life will reset the timer. Good luck!