About the sunflower i think giving her a shootgun or glass canon ability actually benefits the plant side in a positive way.I think there should only be one variant though like an Ice sunflower to not over do the idea but anyways it will allow her to fight back against other zombies and mostly scientists also it helps fend off zombies that try to attack the Sunflowers heal pot.
I heard someone talk about giving the Sunflower a Mech, i'm not totally against it because it'd be cool but i think mechs are game breaking and are just to overpowered and would cause an imbalance with the imp and they might have to implement a mech for each sunflower which would be to much work for the devs, instead i think a teleport like method in exchange for sun laser or sun beam(healing one) to escape from zombies who try to attack her benefiting the less offensive sunflower classes.