No confirmed female zombies, though some plants are referred to with feminine pronouns and can be killed. None of the plant deaths are very spectacle-ish.
There's a dolphin zombie, but we never see the death of the dolphin, nor can you kill it in gameplay, as it leaves when its rider either jumps over a plant or dies himself.
Bungee Zombie dangles from a rope during the rooftop levels, which could be potentially triggering for those who are sensitive regarding hanging imagery
Sort of? Normally, when a Balloon Zombie's balloon is popped, he will fall to the ground and continue on foot. However, if one spawns over water, no zombie will drop. There isn't even an animation of the zombie falling into the water; he just disappears.
There were nearly zombie children (along with a zombie mother) added to the game, however, this concept was seen as too dark and was replaced with the Imp, who looks (and sounds) small and childish, but is implied to be a very short adult zombie.
Imps are small zombies sometimes compared to children, which raises frightening implications on how they came to be, but are just as likely to simply be small.
Jack-in-the-boxes can explode but they are being held by an adult who is using them to attack you. The tricycle in front of your house is unharmed and even complemented.
The Jack-in-the-Box Zombie will march along, playing "Pop Goes the Weasel," and, if not killed quickly, the box will abruptly pop open, causing the zombie to squawk in shock, followed by an explosion that results in the death of both the zombie and any surrounding plants. (This is unless the box is stolen by Magnet-shroom).
Level 10 on fog is literally bright to dark flashing which is intentionally meant to be disorienting to the average player let alone to epileptics and photosensitive people. I had to make my roommate play that level for me. The sprites (character models) flash slightly whenever hit as well and in the final boss battle when the boss is deafeated the screen flickers
Depending on how high your sound effects are turned up, the Newspaper Zombie’s irritated growl or the yell on the Game Over screen could catch you off guard. Especially as both indicate something very bad.
The mini game Zombiquariun takes place inside a fish tank, and it's filled with zombies. This same fish tank backdrop is used in the Zen Garden for aquatic plants.
The Imp is only vaguely infantile in anatomy, resembling a toddler, and everywhere else (including all subsequent games), they are treated more like mischievous goblins than children.
One zombie, the Jack-in-the-box Zombie, has a ripped straight jacket and is very shaky, implying he's an escaped mental asylum patient. The almanac calls him crazy.
Jack-In-The-Box zombies are called ‘crazy’, wear straitjackets, and are enemies you have to kill (though their explosive attack will probably kill them first).
The Zomboni and Catapult Zombie can have their respective vehicles' tires punctured by the Spikeweed (and its upgrade Spikerock), and unless eaten by Chomper or killed by explosive plants, both zombies' deaths involve their vehicles smoking and shuddering before exploding, accompanied by a loud bang and cartoonish clouds of smoke, exhaust and metal parts.
Zombies can be run over by a lawnmower but it is not graphic. Plants can also be run over or flattened by various zombies/vehicles but it again is not graphic.