The Tomb Raiser Zombies and Camel Zombies are pretty tough, and worse, the Flag Mummy Zombies can heal them, so the player needs to upgrade their plants.
Strategy
Upgrade your plants' level by playing previous levels. Then upgrade them more with Puzzle Pieces and the Oven in your house.
Drag as many plants as you can into the lawn. Use other users' plants to have even more power.