This is how the ending of PVZ 2 should be

Modern day is presented as the final world, but is not actually the final world. The world would have all the original stages and plants to really get the player in that “classic” mood, however, the world throughout progressively gains more and more zombies from each world along with the zombie end of the garden gaining an increasingly obvious gaussian blur effect. The reason for this being that time is getting increasingly unstable due to Zomboss’ abuse of it.

Eventually, the boss fight at the end occurs. It would appear to look like the original giant robot from PvZ1 but it would be upgraded with time doodads. As the battle goes on, Dr Zomboss looses control of time, causing the giant robot to start having pieces replaced by machinery from different time periods. After Dr Zomboss’ defeat, Penny tells Zomboss that he needs to stop due to time getting worryingly unstable, Dr Zomboss says something like “I’ll mess with time all I want, I won’t be defeated again!”. Dr Zomboss uses the time warp escape thing he always did with the previous boss fights, but it doesn’t work, he uses it again, it doesn’t work. After a third usage, reality around him tears apart in a vortex, engulfing the whole screen.

This unlocks the true final word, Time Twister. Dr Zomboss, after seeing just how much danger he has put himself and the world in, finally becomes disillusioned. Although reluctant, he agrees the help the player try to restore time and unwhirl the time twister.

This world would be the most difficult of them all, with harsh mechanics to match the tone.

This world contains the shadow plants for they naturally live in a topsy turvy world (They are shadowy, yet not nocturnal. They also aren’t sunny like most plants) and because they have the sense of community to survive a harsh climate (their synergy).

The zombies would be horribly deformed, with limbs in wrong places and misshapen facial features. The special zombies that inhibit this world would be chimeric amalgamations of zombies from the previous worlds to make new threats, like a “Ragonfly-achute zombie” (It is a mix between the ra zombies, dragonfly zombies, and pilot zombies from Lost City. They drop down randomly over the garden, steal a sun, and then get carried by the dragonfly on their back).

The world gimmicks I came up with would be the rifts from original modern day, a mechanic the changes the look of the level to a previous world to gain the mechanics of that world (The twister background changes to a pirate seas one to replace half the garden with planks and gaps), and a twister that appears periodically to move the player’s plants around in a fashion like a “beghouled twist swap” if you know what I mean.

The final boss would show the twister garden split in half by a large, horizontal rift. This rift is the one that tore reality asunder. With Dr Zomboss on the right, and the player on the left, the objective is to defeat anomalous zombies and to let anomalous plants be destroyed by Zomboss. During each bar of “health” that Zomboss usually has, the background changes to a previous world (Ancient Egypt being first, and Modern Day being last) with this background being what plants and zombies must remain, any plants and zombies that are not from the world must be destroyed. The exact way this will happen isn’t fully thought out in my head, but it would make sense for the Time Twister to be destroyed once all the anomalies are gone.

With the unraveling of the Time Twister, the screen takes the player back to the modern day. Everything is fixed. Dr Zomboss admits that his plan was poorly executed and disregarded the potential consequences. Crazy Dave gives up on the taco from the start, seeing how dangerous time manipulation is and instead settles with great tacos made by Penny’s scientific brain (or something, I don’t know, this plot line is unbelievably stupid). To celebrate the triumph over the Time Twisted, the plants and zombies have a taco party together as the credits roll. This cutscene, will pan to the same party happening over the other time periods of the game to show that even though times may change, Plants and Zombies never will.