Here's a 10 Cob setup for Survival: Pool (Endless) that I've played with in the past. I've gotten to 222 flags with it, and then got bored.
You know that really annoying level, 4-10, where it's storming and you can't see anything? When I get back to it on Adventure Mode, I'm planning to use what's technically a hack to put that environment on Survival: Endless. I'm planning to use the setup shown in the screenshot. Slight change. Because I won't need Coffee Bean, I plan to bring Tall-nuts instead so I don't need to Pumpkin them.
Oh, you want to know the hack? In some location on your computer (it won't show up on searches, so I suggest you try researching it; I don't know about any of the PC versions) which is /Users/*username*/Library/Application Support/Popcap/Plantsvszombies/userdata on the MAC version, there are a bunch of files under the name game#_#.dat, where # are numbers. The first number reflects which user's data it is (1 for the first user, 2 for the second, etc.) and the second reflects which minigame/level it's for. game#_0.dat is Adventure Mode. game#_13.dat is Survival: Endless. There are a bunch more, and if you want to know, on any menu, the numbers for each level are counting up by 1 (so if some level is game#_n.dat, then the next is game#_n+1.dat), with the exception of Survival: Endless, which is numbered as if there were also Day, Night, Fog, and Roof Endless (which is technically correct, though those need another hack to produce.)
Renaming them causes another level to read the save file. The environment (Day, Night, Roof Night, Storm, etc.) is not an aspect of the game, it's an aspect of the save file. Therefore, say you're on level 4-10. Its save file is game1_0.dat. Renaming it game1_13.dat causes Survival: Endless to read it, and you've got Survival: Hurricane (Endless), or at least, that's what I call it. Conveyor belts are a bit complicated. Whenever you transfer, the plants on the conveyor belt are the plants you'll have in your lineup IN THE EXACT SAME POSITION, so you can have awkwardly placed plants. The opposite applies when transferring to conveyor belt levels. Make sure your conveyor belt is full, otherwise the game will crash when starting another round of Survival mode.
What about I, Zombie levels? Each plant you plant will turn out a zombie instead on PC versions, but it doesn't work on the MAC version. All the plants that were already there will turn into cardboard.
Wish me luck!