He does not have any traits, and his ability gives him +1/+1 every time a zombie is played or made. This ability stacks with each Unlife of the Party on the field and persists until all Unlives of the Party are removed from the field.
His name is a portmanteau of "undead," referring to the fact that he is a zombie, and "life of the party," referring to his costume.
His description is a pun on "wallflower," which is a shy and introverted person. However, it is spelled as "Wall-Flower," humorously making it sound like a plant from a Plants vs. Zombies game.
This zombie is essentially a stronger Backup Dancer as they both are in the dancing tribe (although Backup Dancer can be used in mustache decks) as well as a powerful ability. Disco-Tron 3000 is a good combo with this, because Unlife of the Party will get +3/+3. Barrel Roller Zombie will also give him +3/+3 for both him and the Swabbies he makes when he is destroyed. This can be alternatively achieved with Triple Threat as Impfinity with slightly more potent results.
If you do not have Disco-Tron 3000 or Barrel Roller Zombie, any zombie that can get out others in one play like Disco Zombie, Mystery Egg or Dance Off are good alternatives, since they give him +2/+2. Imp-Throwing Gargantuar can also help, as every time he is damaged, he will make a Swabbie on the field, which will increase Unlife of the Party's stats. Using zombies that can boost this zombie such as Loudmouth and Coffee Zombie can help out as well.
It is best to play Unlife of the Party only when you can flood the field with multiple zombies during the same turn. Otherwise, he will get destroyed quickly. Play him on an empty lane so he can unleash his full potential. Try to keep him alive as long as possible, as every new zombie that you play or make makes him stronger. You can use health-boosting tricks such as Camel Crossing to keep him alive as well.
Be careful, if he gets too powerful, he will be destroyed by instant-kills like Shamrocket and Doom-Shroom (this can be nullified by Parasol Zombie's ability to give herself and zombies to the left and right of her Untrickable, though only Professor Brainstorm can do this normally without the aid of conjuring.)
Against[]
When this appears unboosted, use any damaging plant or trick to destroy him. However, when he gets boosted, you may use instant-kill tricks or transforming tricks such as Goatify and Transmogrify, however there is a chance that he will transform into another Unlife of the Party when using the latter.
You can also use Shamrocket or Doom-Shroom to destroy him (as well as other strong zombies for the latter) if he gets too powerful. If those aren't options, resort to Bouncing and Freezing, although they are temporary solutions.
In the Brazilian version, his name is instead "Night of the Living Dead."
The roadcone he is wearing also appears in Professor Brainstorm's winning animation, where he puts one on his head.
When being played, his left hand is replaced with his right hand. Also, just before he finishes his "being played" animation, his right hand is once again replaced with his left hand.
If one looks closely, his head isn't connected to his body.
He could possibly be a reference to Conehead Zombie's almanac entry in the original Plants vs. Zombies, where it states that Conehead "likes to party".