Uh oh, he's here. Better get ready. It's gonna be one heckuva fight! Listen, though. I know what his weakness is: You have to hit him in the pancreas! No, that was a different guy...you have to...um...kick him in the...hmm...you have to press up, up, down, down, left, right...er...wait! I remember! It's...
Zomboss' patterns change every battle, this can change the difficulty to harder or easier.
Attacks from Dr. Zomboss are throwing RV, massing Bungee Zombies, and putting down massive numbers of zombies. They are very hard to deal with.
Dr. Zomboss can only be damaged when he brings his face down, during which he sends a iceball or fireball.
The fireballs and iceballs can also crush Roof Cleaners as well as that entire row of plants making that row. Losing a Roof Cleaner due to that will still summon zombies from that lane in order for them to go down to the chimney and eat the player's brain.
Always have an Ice-shroom and a Jalapeno to deal with the Zombot's iceball and fireball attacks and to freeze Dr. Zomboss to defeat him faster.
Do not plant Melon-pults on the first column, and instead plant Cabbage-pults there. This will prevent you from losing the Melon-pults from the Catapult Zombie's basketballs. Try to use a Jalapeno as it is tolerating the roof in the Nintendo DS version.
Try not to keep all your Melon-pults and Kernel-pults next to each other/put them in a square position. Doing this helps keep plants destroyed from the camper dropped by the boss. You will risk losing a last line of defense if this happens. Do not panic planting Cabbage-pults next to each other, as they get killed and appear a little too often.
Only use the Ice-shroom to freeze Dr. Zomboss and put out the fireball, when Dr. Zomboss reaches down to attack you with a fireball, so that your Ice-shroom is not messy.
Do not use a Jalapeno while he is frozen. This will unfreeze him, and let him get away or finish you.
It is also possible to keep re-freezing him with multiple Ice-shrooms before he drops providing an opening for your plants. Butter cannot paralyze the Zombot, though.
If you freeze Dr. Zomboss while he sends out his iceball attack, you will have to deal with the snowball with a Jalapeno, thus unfreezing Dr. Zomboss.
Leave a column of empty Flower Pots on the first slanted lane of the roof as a buffer endless zone and to plant Jalapenos and Ice-shrooms in, and keep your plants behind them, but don't plant them farther up the roof or Dr. Zomboss may kill them.
Plant the Flower Pots on the flat part of the roof when you plant Jalapenos or Ice-shrooms.
If possible, when tough zombies such as Gargantuars, Zombonis, or Catapult Zombies appear, try to wait until they get as close to your most frontal plant before planting a Jalapeno to finish them all. This makes your use of Jalapenos in case Dr. Zomboss wants to put more zombies on the same row.
Dr. Zomboss has a set pattern that he follows at the beginning of the fight. He always places four regular Zombies, four or five Conehead Zombies, then lowers down to breath out a snow/fire ball, then he comes back and places four or five Buckethead Zombies (sometimes he places one Conehead Zombie), then lowers down his head again. After that, the Zombies he places are completely random, except he will not send normal zombies again. After his head lowers the third time, he will then release his Bungee Zombies, then after the fourth, he will drop the RV; after that, his attacks are all completely random. However, they do appear to observe patterns that vary with each fight - some times may include more or less of a particular zombie or attack than usual, or placed in different lanes.
The first few plants you get on the conveyor belt are Cabbage-pults, followed by Melon-pults; try to save your Melon-pults for the Conehead Zombies.
When Dr. Zomboss sends down Bungee Zombies, buttering one makes it unable to steal a plant.
The first four plants on the conveyor belt come out in the following order: Cabbage-pult, Jalapeno, Cabbage-pult, Ice-shroom. The order of plants coming in afterward is completely random.
Kernel-pults are the rarest to come by, so try not to plant them in a same 3x2 area to reduce chances of them being destroyed when Dr. Zomboss throws a camper.
If you have only one Roof Cleaner left, he will put almost all of the zombies in the row with the last Roof Cleaner left.
Remember to spread out Melon-pults and Kernel-pults. If you have one row of all these, the others may not get their fair share of these plants.
Try to have at least 4 columns of attacking plants throughout the battle (except the beginning).
It is recommended to plant a Ice-shroom when the Zombot's eyes turn red, and a Jalapeno when the Zombot's eyes turn blue to counter the ice and fire balls the Zombot sends at you.
When Dr. Zomboss is unfrozen, Jalapeno him, then Ice-Shroom again. This will deal a lot of damage to the zombot, defeating him relatively quickly.