The easiest way to get over 100 points is to shoot a cannon ball on a mountain so that it rolls downward and hits him.

If you are on a valley or on the other side of a mountain, set the angle diagonally upward toward your opponent, set the power to 80, and use a Turn & Burn. If done correctly, you should now be near your opponent. Fire an X-Ray Cannon, Gamma Blaster, Lodestones, Laser (or Super Laser), Bazooka, Late Bloomer, Minigun, or Potholes directly toward your opponent at a high power. You will get massive points by doing this. Also, if your opponent's weapons have too big of a blast, or something that fires particles bound to hit the opponent as well as you, it is going to be difficult for that opponent to gain points. Or, after getting next to your opponent, if you have any dirt weapons (Dirtball, Big Dirtball, Dirt Slinger, Rainbow Dirt, Mud Pie, Tar Ball, etc., preferably Cruball or Mud Pie), and your opponent has nothing to safely remove the dirt, use them. Then, fire any weapons that go through dirt. If you hit the opponent with Flower Power, X-Ray Cannon, and/or Gamma Blaster, you will get a massive number points. Also, not only will your opponent not be able to attack under dirt, but he will have to blast his own points away to get out of the trap.