In order to launch attacks on other players, the player must first train zombies with the Coach Zombie, in a similar way to how they grow plants; although only one wave can be trained at time. Also, they can only have 10 waves at a time. More zombie waves are unlocked as the town is expanded. There are three waves in each attack, and in each wave the player can choose a trained zombie wave to use, and that zombie will then attack along with two other previous zombies. After each wave, a new grave will appear at the farthest point the zombies reached, and that is where the zombies will spawn in that wave. If the player fails to invade the building within three waves, they lose. During combat, they can collect fog that falls from the sky, and spend it on boosting zombies (2x as fast for 3 seconds) or stunning plants (Pausing for 5 seconds). Each use costs 15 fog and fog units worth 25 fog fall as often as sun falls. On the first round the player gets 150 fog to start with. If they ended the previous wave with fog remaining, you will keep that amount plus 150 more fog at the next wave (Example: Ended with 35 fog, next round you will start with 185).
- Winning in a Brainball week's top five gives valuable rewards, such as gems.
- This is the only way to obtain gems without buying them or getting them through promotions in the Facebook page.
- Brainball is the only way to go to other players' towns that are not the player's friends.
- Buckethead Zombies were originally going to appear after Conehead Zombies, Football Zombies were originally going to appear after Buckethead Zombies, and Barrel Zombies were originally going to appear after Football Zombies.
- If the player fails to find any brains, the newspaper clearly shows a Gargantuar Zombie holding an entire house up looking for brains.
- This is the second feature in the series to allow the player play as the zombies. The first was I, Zombie from the first game and the third is Garden Warfare.