Instructions
Use the water gun, which you have by default, to spray Lord Mole, which will discourage him from chewing on the power lines. Lock onto Lord Mole as a target by pressing the red aim button.
Increase the gun's water pressure by sliding the red bar back and forth with your stylus, much as if you were pumping a pressurized water gun. Press "A" to shoot the gun. Continue to spray Lord Mole until he stops chewing on the wires --- it may take a few seconds of intense spraying to get him to stop.
Go talk to Alfred in the hotel to complete your mission, allowing you to get past Lord Mole. Then continue down to the lobby to receive your next mission.