Backup Dancer

The Backup Dancers are the tenth zombies encountered in Adventure Mode, and only appear in groups when summoned by Dancing Zombies. They appear in sets of three or four, surrounding a Dancing Zombie with one on each side while showered by disco lights. Before complaints were made by the Michael Jackson estate, the Backup Dancers and Dancing Zombie used to be a reference to the song (and its zombie-themed music video) Thriller.

Suburban Almanac Entry
 Backup Dancer 

These zombies appear in sets of four whenever Dancing Zombie rocks out.

Toughness: low

Backup Dancer Zombie spent six years perfecting his art at the Chewliard Performing Arts School in Zombie New York City.

Overview
Backup Dancers absorb 10 normal damage shots and their appearances change upon absorptions of 5 normal damage shots before dying at 10 normal damage shots.

Appearances
Adventure Mode: 2-8, 2-9, 2-10, 4-5

Mini-games: Wall-nut Bowling 2, Zombie Trap

Puzzle Mode: Third Vase, ZomBoogie, I, Zombie Endless, Last Stand: Night

Survival Mode: all levels (except Roof)

Co-op Mode: all levels except Co-op Day, Co-op Bowling, Co-op Hard Roof and Co-op Zomboss

Others: Versus Mode

Strategy
Kill or hypnotize the controlling Dancing Zombie, or it will continue to summon Backup Dancers when any of them die. This will also get you an achievement, either Walk This Way, Disco is Undead, or Thrilling the Zombies. Alternatively, plant a Wall-nut in front of the hindmost one or freeze one, because when one stops or is slowed, the rest are forced to follow suit.

The Dancing Zombie will re-summon missing Backup Dancers about every square if any are missing. Backup Dancers will continue after the Dancing Zombie is killed. They form up a square around the Dancing Zombie. Therefore, a Cherry Bomb planted right next to the Dancing Zombie will instantly kill him and at least two Backup Dancers.

Early on, Fume-shrooms are a good idea against them. If you beat Adventure Mode, you can also use the Melon-pult, Squash, or Winter Melon.

Wall-nut Bowling 2 Mini-game
If you place a Wall-nut the moment a Dancing Zombie walks onto the lawn, it should roll past the lead Backup Dancer just as it is emerging from the lawn. If you fail to do this in time, it is necessary to plant two Wall-nuts in quick succession or the Dancing Zombie will have time to summon more Backup Dancers. If there are four Backup Dancers that surround the Dancing Zombie, and you roll a Wall-nut to the front Backup Dancer, it will always ricochet to the next, and then bounce to the back Backup Dancer. This will leave the Dancing Zombie unprotected, leaving an open space (and time) to kill the Dancing Zombie.

Another strategy is to bounce a Wall-nut off of the front Backup Dancer, after which it will usually ricochet off one of the side Backup Dancers (and possibly hit the back one too), and immediately follow the first Wall-nut with another to take out the Dancing Zombie while it is unprotected.

Otherwise, if it is too urgent, you can use a Giant Wall-nut to kill both them and the Dancing Zombie, even though not all of the Backup Dancers will be killed. You can plant an Explode-o-nut to the top or bottom Backup Dancer to kill four of the five.

I, Zombie Puzzle Mode
Placing the Dancing Zombie in the middle lane can help get Brains 2, 3, and 4, in addition to dealing with threats with faster Zombies (if needed) that are vital to part of your success. In ZomBoogie, they are also the most helpful zombie. Only use them in the middle rows (2, 3, and 4) where they are most effective, and try not to get the Dancing Zombies killed. The best way is to start with row 2 or 4, and then do it on the other. In I, Zombie Endless, if you place a Dancing Zombie in a row with no plants, he can't die and will keep summoning Backup Dancers and get the Brains easily.

Trivia

 * If a ladder is placed on a Wall-nut and a Backup Dancer climbs it, it will only dance up to some part of the ladder then pass through it.
 * The Backup Dancer, Dr. Zomboss and the Imp are the only zombies which don't have standing animations. For example, in the Suburban Almanac, the Backup Dancer is still dancing and the Imp can be seen walking in place. Also, in the XBLA version of the game, in I, Zombie, if you spawn an Imp, the transparent Imp will not move.
 * The Backup Dancer received a new model in a recent update to the iPod Touch, Xbox, iPhone, and iPad versions of the game to go along with the Dancing Zombie update.
 * When a Backup Dancer sticks its tongue out after biting a Garlic, it continues dancing.
 * The new Backup Dancer does not stick its tongue out, except in the XBLA version.
 * The old Backup Dancer zombie and the Pole Vaulting Zombie are the only zombies with headbands.
 * If the Dancing Zombie or any of his Backup Dancers are slowed down or paralyzed, the rest of the group will also slow down with it and only move a little.
 * The new Backup Dancer and the Ladder Zombie are the only zombies with mustaches (if mustache mode is off).
 * Mustache mode won't affect these Zombies.
 * The old Backup Dancer's legs change sides when it dances. If it loses an arm, the arms will also change sides.
 * If the old Backup Dancer loses one of its arms, no bone can be seen.
 * In the iOS version, its jaws will break apart when killed. The same thing will happen to the Dancing Zombie.
 * Due to the fact that the Dancing Zombie summons them, the Backup Dancer is one of nine zombies not available for selection in Versus Mode. The others include the Zombie Bobsled Team, the Balloon Zombie, the Zombie Yeti, the Imp, Dr. Zomboss, and all three aquatic zombies (the Ducky Tube Zombie, the Snorkel Zombie, and the Dolphin Rider Zombie).
 * The Backup Dancers and the Zombie Bobsled Team are the only zombies that appear in groups of four.
 * They are also one of the Zombies that can be avoided in the Suburban Almanac.
 * The Backup Dancer, Imp, Zomboni, Gargantuar, Giga-gargantuar and Dr. Zomboss are the only zombies that don't have the word "zombie" in their name.
 * The Backup Dancer, the Zombie Bobsled Team (except for Bobsled Bonanza), the Flag Zombie and Dr. Zomboss are the only zombies that don't appear in the Seed Selection Screen.
 * When a Backup Dancer gets to your house, and when it is only halfway through the door, you can hear the crunching of the zombie eating the brain, even though it hasn't entered the house.
 * This also happens with the Imp and the Zombie Yeti (Through Hacking).
 * The new Backup Dancer dances a different way like the new Dancing Zombie.
 * If a Dancing Zombie is frozen with an Ice-shroom just at the moment it summons Backup Dancers, the Backup Dancers will be frozen, but will not be blue or have ice crystals on their feet.
 * The word "Chewliard" from the Backup Dancer's almanac entry is a pun to the Juilliard School in New York City.
 * The Backup Dancer is one of the six zombies that falls backwards when it dies; the other five being the Zombie Bobsled Team, the Dancing Zombie, the Football Zombie, the Giga Football Zombie and the Balloon Zombie.
 * In Wall-nut Bowling 2, a Wall-nut placed in the row with a Dancing Zombie will bounce of the front Backup Dancer and hit at least one other Backup Dancer unless there are a group of zombies where the Wall-nut bounces to.
 * The Backup Dancer, the Zombie Bobsled Team and the Imp are the only zombies that depend on other zombies to be able to attack on your lawn.
 * There is a glitch with the new Backup Dancer that sometimes, when the new Dancing Zombie summons a Backup Dancer while an other Backup Dancer is crunching an other plant, the summoned Backup Dancer will freeze with the movement for a second.
 * In XBLA, PSN and DS versions of Plants vs. Zombies, the new Backup Dancers are about as tall as a Gargantuar. This also happens with the Dancing Zombie.
 * The old Backup Dancer is called the 80's Zombie in the Plants vs. Zombies Trading Card Game.
 * It's somewhat similar to the Conga Dancer of Plants vs. Zombies Adventures.