The Tomb Raiser Zombies and Pharaoh Zombie are really tough, so the player needs to upgrade their plants.
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. Charging plants (e.g. Potato Mine, Grave Buster, Iceberg Lettuce) should be useful on focusing maximum attack power on the boss