Bun Bun Symbiote (Alien/Floating)

Enemy
Bun Bun Symbiote is the alien variant of Teacher Bun Bun.

It has extremely high health and damage, with fast attack rate. He is a bit harder to defeat than the other Bun Bun varients, due to him having half as many knockbacks. Even worse, he has a chance to create a lv1 shockwave.

While the shockwave is rare, it can destroy your meatshields, and your long-range attackers due to his high damage.

He first appears in Into the Future Chapter 3: The Great Abyss

English Version
Bun Bun's DNA got bonded with an alien creature. Infected students with it too. Now school is one big hive mind (Source: Hippoe) Occasionally fires a powerful energy wave.

Strategy
Even though it can only create a Level 1 Shockwave, this still greatly increases his range, killing all of your Dragon Cats, Ururun, Bahamut, and knocking back any Ubers that you may have.

Bring as many anti-floating / anti-alien freezing units as you can, like Castaway Cat, Delinquent Cat, or Akira (Uber Rare Cat). This can help lessen the chance of a shockwave occurring.

It helps to also bring powerful alien/floating resistant units like Sodom and Mekako Saionji. (Normal form only for the latter). These units can withstand hits from shockwaves.

Reference

 * http://battlecats.spica-net.com/enemy/213.html