One of my favorite plants in Plants vs. Zombies is the Chomper Plant. This guy isn’t the best overall plant, but he’s one of the most fun ones. Basically, he is a single kill plant that eats up zombies whole. He can kill any zombie except the Gargantuar and Dr. Zomboss (the big boss at the very end). Anything else is lunch. The chomper can even eat zombies from a full square away, meaning that you can set up a Chomper behind a Wall-nut or Tall-nut and it will gobble up from a safe distance.
The really important thing to know about the Chomper, though, is that while it’s chewing and devouring a zombie it is very vulnerable. The Chomper needs about 45 seconds to fully eat a zombie so during that time it’s ineffective. You’ll really need to protect Chompers while they chew. A common technique is to place your Chompers behind a row of Wall-nuts. They’ll eat the first zombies that approach the Wall-nut line and then will have enough time to finish their snack and eat again. Of course, Chompers aren’t enough of a defense by themselves, but they are great for taking out the tougher zombies like the Bucketheads and the Pole Vaulting Zombies.