Plants that PvZ 3 could add

Toffee-pult  5 sun launches caramel Kernels and blobs that damage and slow zombies in a 3x3 area

podfather: 5 sun gives all pea plants extra damage

speedflower: 3 sun produces 1 sun and occasional speeds up plants around it over time

metalflower: 4 sun high health and produces sun

recharge lily: 4 sun all plants except for itself has it cooldown finished 

King shroom; 8 sun shoots piercing poisonous spores and occasional spawns puff shrooms

Dark flower: shoots flaming sun at zombies and does damage based on how much sun you have