The pea Shooters are not overpowered. Heck when they introduced the game the producer was asked to give his IDEAL plant team. He suggested 6-8 pea shooters and 2 of every other class. They are meant to be the main force. The problem with garden and graveyards is the cap is to fast for the zombies. Most game people won't play as sunflower. If there is no sunflower on your team you should be the F'ing SUNFLOWER OR YOU OR YOU ARE GOING TO LOOSE.
Ps When you are playing as plants you should RUSH THE TELAPOTER for the zombies. If you can Prevent teleporter from going up you will win the game. But noone ever does......they just let the zombies build it and then they cap the garden with EASE. People just need to learn how to play the game.