We usually don’t give advice for end boss battles in Plants vs. Zombies 2. Why? Well, they always feature a conveyor belt and basically require you to immediately position whatever plants you get and let the chaos ensue. Additionally, we never find them particularly difficult, if yet challenging and fun. Things are a little different in the Jurassic Marsh end battle. Not only was it one of the more difficult fights against Zomboss, but it also required a fair amount of tactics.
On the conveyor belt, you will find Primal Peashooters, Perfume-Shrooms, Chard Guards, Primal Potato Mines, Primal Wall-Nuts, and Bonk Choy. You will meet all the zombies from your journey through the Jurassic as well as all the dinosaurs. The tricky part about this level is the amount of dinosaurs that you will encounter. In the beginning, you will face mostly Raptors and maybe a Stegosaurus here and there. If you can’t easily defend yourself against the Raptors, then feel free to use whatever Perfume-Shrooms you get on them, but believe us when we say that you will need them later on in the battle. The second round of the fight introduces the Pterodactyls. Use any Perfume-Shrooms you have on them. There will often be two in a lane, so prioritize those. The third stage of the battle brings out the T-Rex, which are accompanied by Jurassic Gargantuars. Try to save a Perfume-Shroom when possible to use in those cases, as it will prevent the Gargantuars from reaching your defenses quite as quickly. The enchanted T-Rex will also help you fight against the behemoth.
Towards the end we found ourselves fighting against up to four Gargantuars at once. At this point, you should not get disappointed when losing a lawn mower here and there. As we found ourselves nearly overrun by zombies, we focused our last attention on Zomboss himself and defeated him before the Zombies were able to breach our defenses.