The biggest challenge is at the pool's lanes with threats coming from Dolphin Rider Zombie which will jump into the water and emerge at the second plant out of water. If you do not manage this properly, you will end up losing the pool's defense.
To do this properly, make use of pumpkin to protect the plant.
Another tips is to try to make use of double headed sunflower to give you double energy and save spaces.
The third tips is to always put a shooting plant at the last plant at the edge of the house. This is so that the last defense will always be something that is shooting the zombie in case of those jumping zombies or those which can dig the floor and penetrate your front line of defense.