Plants vs. Zombies is a very classic tower defense game. Players need to arrange plants reasonably in the game to resist zombie attacks. The following is a schematic diagram of how to draw the troops in Plants vs. Zombies:

1. Prepare canvas and drawing tools. You can use paper and pen, drawing board and brush.

2. According to the map and scene of the game, divide the canvas into several grids, each grid represents a grid in the game.

3. Draw plant patterns in the corresponding grid according to the plant types selected in the game. Simple lines and colors can be used to represent different plant species such as pea shooter, sunflower, ice shooter, nut wall, etc.

4. Draw zombie patterns around the plants to indicate their attack routes and attack methods. Different colors and lines can be used to represent different zombie types, such as ordinary zombies, roadblock zombies, iron barrel zombies, etc.

5. Arrange your troops reasonably according to the rules and strategies of the game, for example, place defensive plants such as Nut Wall and Small Spray Mushroom in the front row, and place offensive plants such as Pea Shooter and Ice Shooter in the back row.

6. Finally, you can add some decorations to the pattern, such as iconic elements of the game, plant and zombie expressions, etc., to make the pattern more lively and interesting.

It should be noted that this is just a method of drawing a schematic diagram of troop formations. Specific game strategies and layouts need to be adjusted and optimized by players based on their game experience and skills.