There is no special way to easily defeat the teapot. It must be defeated simply by attacking it for a very long time, and therefore is mostly just best to leave Candy Box 2 running while facing the teapot and then coming back to your computer a few hours later. Make sure you have all of your weapon slots (Weapon, Hat, and Gloves) filled, of course. Make sure you have your weapons enchanted, if you feel the enchantments are necessary. If you're using items that cast fire balls (like the Red enchanted gloves), picking up the Red shark fin (obtainable from killing a certain shark underwater from The Pier) before your battle with the teapot will be a big bonus, as it increases the damage of fireballs cast by the player.
Something else that is important to remember for some is to not wear the enchanted knight body armour. While it provides an amazing percentage of damage reduction, it cuts your attack in half. And the teapot does not attack at all, so wearing armor when facing the teapot accomplishes nothing, and only hinders you in the case of enchanted knight body armour, as you need all the attack strength you can get.