Okay. This is a strategy for Survival: Pool (Endless). I found this strategy on Baidu, and wanted to try it out. So how does it work?
The bottom row's the best defended and the worst defended. First of all, that Spikerock gives you room to make mistakes there. However, it's much easier for both varieties of Gargantuars to get there and damage it.
In the pool, just watch out for Dolphin Riders and Ducky Tube Bucketheads. I lost a Gloom-shroom to a Buckethead once.
In the inner rows, one instant and Gigas should die on their own.
The top row is also the best and the worst defended, in certain situations. If there are Screen Door Zombies or Zombonis, get ready for some serious cobbing. Ladder Zombies and Catapult Zombies you can react to, too, but they're lower priority.
So how do you play this? First of all, repair Pumpkins. Buy Crazy Dave's Wall-nut First Aid. Without it, you have to either wait for a Pumpkin to get eaten, in which case the plant inside it is vulnerable until you replace it, or you have to dig up the Pumpkin, and in this situation, it's also temporarily vulnerable. Imitater Pumpkins are also pretty much mandatory.
Also, make sure that Spikerock gets replaced when destroyed (which isn't very often.)
But here's the biggest part: the usage of instant kills and Ice-shrooms. Okay. You can come up with your own way, but here's how I do it. Repeatedly
Wait 18 sec and fire a pair of cobs, one to devastate every Gargantuar on the top half and another to hit everything on the bottom.
Wait 18 sec, then fire one cob, with a Cherry Bomb to substitute for the other.
Wait 18 sec, then fire a pair of cobs.
Wait 18 sec, fire one cob on the top half of the screen, and Coffee Bean an Ice-shroom the instant it lands.
This is only necessary in levels with Gargantuars, Gigas, Screen Door Zombies, or Zombonis. It's possible to not need to do this when there aren't just Gigas, though your plants are a bit more vulnerable. Also, see those Gloom-shrooms in the back that take care of Diggers? EVERY GLOOM-SHROOM other than those can be blown up by Jack-in-the-box Zombies, if they get far enough to have them in range, but aren't given enough time to die. Always bring Lily Pad, Fume-shroom, Gloom-shroom, Pumpkin, and Coffee Bean when there are Jack-in-the-box Zombies. Even when you're only at 12 flags. You could get wiped out as early as then. I've seen an instant Jack explosion that early three times. Luckily, none of them were in the inner rows.
Oh, and Bungees. Use an Ice-shroom to freeze them as soon as they come down. Make sure they're frozen to the spot. Bungees that target the Torchwood get unfrozen unless a Bungee targets the Gatling Pea right behind it, but don't worry too much about them. They're pretty much doomed if they're in range of all the Gatling Peas.