Highway to Danger

This is nighttime. No sun will fall, mushrooms will be awake. In 5-5, it is the minigame Squashy Horror. 5-10 is the conveyor belt level, and 5-11 is the boss battle.

Plants
5-1 Sun-shroom

5-2 Fume-shroom

5-3 Scaredy-shroom

5-4 Squash Seed

5-5 Cactus

5-6 Blover

5-7 Low-shroom

5-8 Doom-shroom

5-9 Skull

5-10 Boss Battle Intro

5-11 Samurai Sword

Zombies
5-1 Cultist Zombie

5-3 Squash Zombie

5-6 Cursed Zombie

5-8 Crawling Zombie

5-8 Winged Leech

5-11 Zombie Conjurer (Boss)

Trivia

 * Most players would consider this world easier than the previous ones.
 * It is probably because it is a Night level, which is the second level in the original game.
 * It also could be that the zombies introduced are easy to deal with.