Bitter Dill's primary attack are the Bouncy Seeds, he spits out seeds that bounce off the walls and floor. He can fire 10 seeds per sequence and each seed knocks away zombies that are hit by it.
Abilities
Goop Spin: If a zombie gets too close, Bitter Dill will spin around and create a cloud of Grody Goop around him. Much like Bouncy Seeds, knocks the player back.
Grody Goop: Bitter Dill will sometimes spit out an onion, this onion acts similar to Chomper's Grody Goop, as it slows zombies, makes them unable to use abilities, and deals toxic damage.
Elite Wave
During Bitter Dill's elite wave, he spawns Weeds, Wildflowers, Kernel Corns (wearing the Leaf Cadet hat), and Cacti (wearing the Succulent Braids hat) after the players.
When Bitter Dill loses a fourth of his health, he will become briney, which makes him invulnerable. He will drop a mint that somebody has to pick up and take to a soda trap. When briney, Bitter Dill doesn't shoot Grody Goop or Bouncy Seeds, he only chases after players and does Goop Spin. Once Bitter Dill is hit with the soda trap, he will become vulnerable once more. Players have 10 minutes to defeat Bitter Dill. When the timer runs out, the player's group will fail the wave.
Strategies
Bitter Dill can be a very annoying opponent; his tendency to bounce all over the place and his relatively small hitbox (for bosses) makes him difficult to hit.
To make matters worse, his main attack will knock you backwards, possibly off a cliff or into some other obstacle, or could just mess up your aim and prevent you from landing any hits on him. Plus, Bitter Dill can spit out pools of goop (similar to the Chomper'sGrody Goop) that can prevent you from moving or using your abilities. As such, to defeat him, it is recommended to have at least two Zombies teaming up against him so one can attack while the other is being thrown backwards.
Try not to play as Super Brainz, as Bitter Dill's knockback will prevent you from being able to deal any melee damage. All-Star is a good character to use, as his high health allows him to take the hits while the other Zombie attacks. His Dummy Shield can also help him block his various attacks.
Space Cadet is a good choice for the second Zombie, as she can use Crater Maker while being a Space Station to easily deal lots of damage to the Bitter Dill, while being immune to being knocked back.