As someone who's main plant class is the Pea Shooter, I agree completely with OP. What was the purpose of giving plants 2 fully-leveled characters (Pea Shooter already being the most OP breadwinner of the plants to begin with) for nothing? Why did zombies recieve no fully-leveled characters with the promotion either?
Pea-Shooter was already OP as hell, this promotion was uncessesary just as an advertisement. Since the release of the Aquafina characters, I've completely stopped playing normal mode and stick to classic, 99% of Pea Shooters are the Berry Shooter now for obvious reasons. The only Pea Shooters who don't play the Berry Shooter are just checking out other Pea Shooter variants they got, before promply switching back to Berry Shooter.
Stupid idea. They need to remove the full upgrades or balance the damage output.