Plants needed: Starfruit, Puffshroom, Imitater puffshroom
Note: Fill in the other seed slots with plants you don't use
Difficuilty: Very Hard
When the first zombie comes, use a puffshroom to delay him. Then, collect the sun until you can plant a star fruit and you have to ALWAYS delay that zombie. When the second zombie comes, repeat the process. When coneheads and bucketheads appear, delay them even more than you delay normal zombies. But, when there are hordes of zombies just delay where there are more zombies.
