Unfluffables

The Unfluffables are a Deer and Rabbit duo found in Secret Island. Despite their species they are twins, yet very little is known about them. They attack Roofus shortly after he approaches them and gives them a stare down.

Strategy
In the Dreamcast version, you can easily defeat them by freezing them and shooting them afterward, quickly ending the fight. Otherwise, they are limited to Close Attacks, so attack from a distance. But beware of the surrounding Grondas and Shrimps.

If you are desperate to save ammo, you can try to force them to battle the Grondas, since Grondas are invincible to them. After a while of getting hurt by them, they will eventually stray away from Roofus and attack the Grondas instead.

After a while, they will eventually fall, and you can continue on your journey. Their health isn't connected though, so defeating one will not automatically defeat the other.

Trivia

 * The Unfluffables are parodies of two women from the James Bond film Diamonds Are Forever, who are named Bambi and Thumper. This is seen in their outfits, attack style and what they are referred to in the game files (BAMBI and THUMPER). Their species is a reference to the Disney movie, Bambi.
 * In the Dreamcast version, you do not have to play as Roofus to fight them.
 * There are fluffable versions of their species found throughout the game, but they do not seem to possess their level of intelligence. It is possible that General Viggo mutated these two.
 * For reasons unknown, watching their introductory cutscene all the way through can lead to a peculiar glitch where Roofus will become completely invulnerable in Fur Fighters PC and Viggo's Revenge.