This level features Buckethead Zombies, Pole Vaulting Zombies and two huge waves of zombies. As it has many powerful zombies, it may be a challenge to newer and inexperienced players. It is easy as long as the player uses effective strategies to deal with Buckethead Zombies.
Try to place two columns of Sunflowers, one column of Peashooters, one column of Repeaters, one column of Snow Peas, and one column of Wall-nuts to defend all of the plants.
This will defend off all of the Buckethead Zombies and Pole Vaulting Zombies.
If a zombie eats through all of your defenses, you have a Lawn Mower to kill all of the zombies in that row. Zombies will not spawn on that row for a while, so it will give you time to fix your defenses.
Plants vs. Zombies Wiki has a gallery for Level 1-9.