Would it be appropriate for a T rated game? Would it fit into the Bully universe? How would Jimmy even react to a zombie outbreak?
In a cartoon violence way, probably. Zombies Ate My Neighbors exists (and is rated Everyone, IIRC) and you have two teenagers going around using water guns and other weird weapons on zombies + other horror-movie monsters.
I imagine however, the gameplay for Bully would be the same. Hand to hand combat might be axed in favor of using the weapons the game already has (slingshot, spun gun, baseball bats). It would basically be like chapter 6 where everyone hates you and rushes at you from 50 feet away. I can maybe see it as a mini-game. The best I can come up with is a sorta holdout thing where clones of students/adults come at you and after a few waves you win.
And honestly, no thank you. I can beat everyone up just fine without them being zombies.
Zombies are lame anyway.