The Cardboard Scenario brings us PvP and ZvZ

In the first Plants vs Zombies game (PC), there was a puzzle mode where Crazy Dave set up cardboard plants and the player had to "plant" zombies.  The goal was to eat/get past the plants and eat the brain at the end of each of the five rows.

So, for PvZ:H, someone could choose cardboard mode when they select their plant or zombie hero.  When this happens, the cardboard plant player plays against a regular plant player, but the cardboard plant player plants and uses tricks during what is normally the zombie player's turns (cardboard plants -- regular plants + regular plant tricks -- cardboard plant tricks).  Of course, it is vice versa for the cardboard zombie player... the cardboard zombie player plays against a regular zombie player, and the cardboard zombie player plays zombies and uses tricks during what is normally the plant player's turn (regular zombies -- cardboard zombies + cardboard zombie tricks -- regular zombie tricks).

Visually, the cardboard plants/zombies and tricks would be look flat (not so 3Dish as it is now) and be slightly outlined/bordered to suggest that they are cardboarded.  Animations would be the same as they are now; however, that cardboard look would continue to apply.

This would open up a whole new set of vs battles without having to add more heroes to the game.