I just finished playing 35 rounds of this game. It's way too hard.
We won once, got 15 Rainbow Stars and a sweet blue crown for Corn. It seems like if one of your teammates don't know what they're doing it dooms the entire thing to failure. We won with two sunflowers, a corn and a peashooter.
Tips:
Save your 3 insta-revives for only during the popsicle rounds. Stay close to teammates at all times up until just before the popsicle part, then split up so the map is covered easily for when they appear. Don't take on the jester until everyone is together, and the closer the jester is to the Yeti king the better (less walking and you'll have more time). The yeti king does not have to be in the orange spring circle, but your teammates do! Use long range plant pots, I especially liked the goop one because it slowed down those awful zombies from freezing me.