Weevil

The main method of defeating Halloween (at the beginning of the game) is to pick up the clown nose bombs and throw it back. Then use your ridepod to attack it while it's stunned. Avoid it's missiles by running around it in circles. The Flotsam Balloons can also be taken out with your ridepod.

Use healing items such as Bread during the battle. You can usually find them in the crates scattered throughout the other levels in the sewers. Or you can buy them from the bakery.