Don't Pea in the Pool

Strategy
This is a very simple achievement to unlock, but there is little point in trying it until you beat Adventure Mode. However once you do all that is necessary is to replace Peashooters with Cabbage-pults, Kernel-pults, Cactus and/or Melon-pults. Cattails are also good to use since they can attack every lane, but this is not recommended for Pool's Closed. Chompers can work too, since they're a replacement and can be used for this achievement before finishing Adventure Mode. If you have a Coffee Bean you can use Scaredy-shrooms, Puff-shrooms, Sea-shrooms (if you want to plant in the water), or Fume-shrooms. It is possible to get this and the achievement Pool's Closed, by using area of effect plants such as Starfruit and Gloom-shrooms alongside the pool. Overall, you should try for this achievement on Level 3-1, after you completed Adventure Mode at least once. You can still earn the achievement without finishing Adventure mode on level 3-1, by using Chompers, Lily Pads and Wall-nuts, since they protect the Chomper, and there is no zombie that is a threat on the level. Completing Survival: Pool (hard or easy) while using a Survival: Endless build will also work as well.

Note: Completing a Fog level without using any peashooting plants will not unlock this Achievement because it is not day, nor Pool, but Fog. Also, completing ZomBotany 2, Last Stand, Zombie Nimble Zombie Quick, Bobsled Bonanza, or other Pool Mini-games doesn't unlock it, either, only Adventure Mode.

Trivia

 * Don't Pea in the Pool is a reference to the rule "Don't pee in the pool".
 * Don't Pea in the Pool and Pool's Closed are the only achievements that restrict planting certain plants in the pool levels.
 * It is possible to get the achievement on Last Stand on iPhone/iPod touch versions.