In the Hard Mode of this level, the player has to beat the zombies at Level 2 or above, along with no lawn mowers.
Although the Pianist Zombie and Chicken Wrangler Zombie are both levelled up, it would be not much a problem with Lightning Reeds and Spikeweeds. However, the Chicken Wrangler Zombie can cause the player to lose concentration on defeating other hordes of leveled-up zombies.
Required plants: (All levelled up)
Do the things you need to get ready.
Plant Snow Peas and Kiwifruit to attack. Plant Lightning Reeds and Spikeweeds to weaken the zombies, as well as to kill the two biggest threats in the level.
You can also plant some Magic Mushrooms to attack backwards and use its Plant Food effect to summon zombies to stall and deal damage.