Rework Rest in Peace mode and Cloudy day 🧟♂️☁️
Something I'd like them to work on again is increasing the difficulty of Rest in Peace mode by removing all lawnmowers and adding more zombies, maybe even including Giga-Football Zombies.
This mode is supposed to be harder, but I'd like it to be even harder.
And in Cloudy Day mode, all mushroom plants (yes, I know mushrooms aren't plants) should have their sun cost increased by 15 when it rains. This is mainly because of Puff Shroom, and it should be usable as a shield when it starts raining in that mode. This is more of a nerf for Puff Shroom in that mode.
Maybe you could also play with twin sunflower in that mode. I even drew a picture of what it would look like in Cloudy Day mode, referencing Doduo from Pokémon when it's asleep. Also, just one Sunflower only produces 5 sun.
One sunflower from Twin Sunflower goes to sleep; it can be either the left or right one to vary sleeping sides.
I think that's all they could improve about the game besides fixing a few bugs. I'm not mentioning Zombatar because I hope they add it in the future with more content. The only thing I don't think they'll add are the Plants vs. Zombies minigames on the DS because of the exclusivity, and we all know how Nintendo is.