From the Super Mario Wiki
The level is a redone version of Level 2-DK, though with additional spikes the player has to avoid. To damage Donkey Kong, the player needs to drop fruit onto him as he moves on a platform below. Every time he's hit, he moves faster for a brief moment while throwing up Snapjaws. After the third hit, Donkey Kong will move at his fastest constantly. Hitting Donkey Kong four times will defeat him and the player can move on to Fire Mountain Plus.