What I've been waiting on since the release of this game is the Feudal Japan level...
Sumo Fighter Gargantuans.
Samurai Helmet - Bucket Zombies.
Ninja that rush the first plant in a lane and slash it with their sword, then stalk forward menacingly.
Ninja that drop a smokebomb and reappear in another lane.
Geisha Zombies
Japanese Archer Zombies who sit back at the start of a lane firing arrows at plants or ninjas with throwing stars...
Basic Zombie in a Karate Uniform with a black belt.
I mean, come on! How can we ever get to Pirates vs Ninjas if you don't ever give us NINJAs?