To handle the ambush zombies (the zombies who appear from the pool out of nowhere), I use my cob cannons. I fire the cob cannon 7-8 seconds after the last sign appears. You can also use Ice-shrooms and Doom-shrooms, but I prefer to use my cob cannon.Ballon Zombies most of the time will be killed by the cob cannons. If some pass, use a Blover. I would not recommend Cattails as they sometimes pop the ballon and the Ballon Zombie lands on my cob cannon, eating it.
Miner / Digger Zombies get killed by the Gloom-shroom at the back, and it requires no repairing since they won't be able to reach the pumpkins. Miner zombies don't climb ladders.
Bungee Zombies can be handled pretty easily. The only plants they can steal are the Tallnuts on the pool. Use cob cannons on these. Did I mention Bungee Zombies will also die if you fire the cobs on the 2th and 5th row, last / 9th column?
If there's a situation where you don't have any cob cannons available, use cherry bombs.
Giga-gargantuars (or normal Gargantuars) are not very dangerous. If some get close to your cob cannons, distract them with Puff-shrooms or kill them with a cob cannon.
Catapult Zombies are no threat at all since the basketballs they shoot can't reach the plants as the Umbrella Leaves protect the plants.
Take caution of Pogo Zombies. They're fast and can jump over the cob cannons. The Winter Melons and the Gloom-shroom should kill them.
Jack-in-the-box Zombies die MOST of the time before they can blow up my Tallnuts. If you see a round with them, kill them ASAP.
Dolphin Zombies are no threat as they can't jump over the Tallnuts. Kill them with the cob cannon.
Snorkel Zombies are kind of dangerous since they eat fast the pumpkins.
Zombonis are no problem since they are killed from the cob cannons.
You shouldn't worry if Pole-Vaulter Zombies jump over the cob cannons, as the Gloom-shroom will kill them.
Dancing Zombies (more specifically Backup Dancer Zombies) are extremely dangerous, because they can eat the front 4 cob cannons. I usually fire the cobs on the 2th and 5th row on the 8th column to deal with them.
The plants I bring EVERY round are:
Lily Pad, Squash, Cherry Bomb, Pumpkin, Imitator Pumpkin, Kernel-Pult, Cob Cannon, Tallnut, Blover and Puff-shroom (to distract the Gargantuars).
If you REALLY want a no repair setup, you can replace the Tallnuts in the pool with only a Lily Pad, however, take caution of Snorkel Zombies.
You don't need to worry for sun, since there are 4 Twin Sunflowers in this setup. If your sun drops low, though, place 4 Twin Sunflowers at the back when there's a round without Miner / Digger Zombies and without Catapult Zombies.
Ladder Zombies are useful since they ladder your pumpkins, making them invulnerable to zombies, but then again, their speed sometimes gets them bitting my cob cannon. Make sure the Winter Melon slows them down and then cob them.
When there's a Gargantuar (or Giga-Gargantuar) alive, and no other zombies alive, distract him with a Puff-shroom. This helps all the cob cannons be ready and charged up for the next wave.