The Zombot can eliminate defenses within two rows plus it will spam by summoning zombies once it one-third of its health has been diminished. Because Mummified Gargantuars also appear, it will be difficult to handle because there are no ice-plants given that will slow them down, save for Iceberg Lettuce. The ability of the Zombot to create a tombstone also contributes to the difficulty because it create two tombstones at the same time along with Tomb Raiser Zombies.
Once two-thirds of its health is gone, it will call Explorer Zombies and Pharaoh Zombies to clear out defenses quicker because Explorer Zombies burn all plants in one touch and Pharaoh Zombies pack a lot of health, despite its slow speed.
Repeater is your best plant to damage Zomboss with Plant Food but if there are gravestones nearby, Bonk Choy is better instead.
It is recommended to keep one Iceberg Lettuce, one Grave Buster, and one Plant Food at all times. This way, you can quickly remove tombstones that show up in bad places, and you can use Plant Food to counteract the Sphinx-inator's charge attack.
The Zombot Sphinx-inator will almost always send his zombies in tight clusters. Imp Mummies and Mummified Gargantuars are not sent until phase two (when one-third of its health is gone), and Explorer Zombies and Pharaoh Zombies are not sent until phase three (when two-thirds of its health is gone). Try to take care all of them with a Bonk Choy fed with Plant Food in between the zombies. Do not plant the Bonk Choy in the middle of a Zombie stack or it will be eaten, unless if you can quickly put a Plant Food on the Bonk Choy which is in the middle of a Zombie stack, it can kill all the zombies with ease.
Never waste Plant Food. If one appears, and you still have Plant Food, use one if it is needed, and then pick up the additional Plant Food.
In lanes where you are about to lose, place several plants there, so the Zombot Sphinx-inator will kill the zombies.
Always try to stall dangerous zombies, such as Explorer Zombies, Pharaoh Zombies, and Mummified Gargantuars. Use Iceberg Lettuces, Wall-nuts, or both to your advantage to stop them.
Do not be afraid to use Power Ups if you are about to lose.
Try to use Iceberg Lettuce when the Zombot Sphinx-inator is at a lane with many strong plants. It cannot freeze the Zombot Sphinx-inator, however, but rather just slow it down.
The Zombot Sphinx-inator takes up two columns on the right of the screen. Watch out! If you plant a Bonk Choy in the third column from the right, the Zombot Sphinx-inator will sometimes move into the third column and trample any plant within its range. Always keep at least one Plant Food and be prepared to stop Zomboss from trampling your Bonk Choy(s). Learn to anticipate when it will make that move.
When its target locks onto a plant, use Plant Food on that plant to keep the missile from destroying that plant.
For Bloomerangs and Cabbage-pults, only use Plant Foods when the missile almost lands on it because they have a short Plant Food duration.
Keep Bonk Choys up at front and use Plant Food on them when Zomboss is close.
If Zomboss charges down two lanes full of zombies, make sure to give plant food to the plant closest to the zombies. If done correctly, it will stall Zomboss just as he finishes trampling the zombies.
If you have a Repeater on the lane which Zomboss is where there are no tombstones and you have a Plant Food, use the Plant Food before Zomboss leaves the lane. This can deal a lot of damage to Zomboss.
If it gets too crazy, Plant Food the Iceberg Lettuce.