Generally, use the same strategy as Level 2-3. The only difference is to try to plant Wall-nuts (or Puff-shrooms, if you do not want to use sun or if you want only a temporary defense) to let Pole Vaulting Zombies use their poles and move regularly like other zombies.
Use Grave Busters to destroy graves whenever you have a sufficient amount of sun. This will prevent zombies from spawning at the final wave. You will also earn a some money (either a silver coin, gold coin, or diamond) every time you destroy a grave.
It is not recommended to use Sunflowers, as they produce sun more slowly, making the level harder.