Bifrost the Crocoroid

Bifrost the Crocoroid (バイフロスト・ザ・クロコロイド) is a large ice-element Pseudoroid developed for base defense. He is based on a crocodile, as his name implies. His primary function is stopping enemy advances, as opposed to destroying enemies, so he has been equipped with a wide-area effect freeze weapon, known as 'Giga Freeze'. He is capable of opening his mouth to a complete 180' angle, and firing his teeth as icy missiles, and is also capable of launching saw-like blade wheels ala Wheel Gator, although his most dangerous attribute is his sheer size. Also note that when his mouth is open, it acts as a shield and many of the player's attacks will not be able to penetrate.

Grey and Ashe's first encounter with Bifrost was in the Bio Lab. After stumbling on a room full of sleeping Mechaniloids, Bifrost exposes that they were actually born in this area, and that they will activate when the Mega Man King arrived, and intends to crush Biometal Model A into pieces in the meantime. After he is destroyed, he expresses shock at his loss, and wonders if it really is Model A who will become the Mega Man King. Bifrost is later revived by Biometal Model W and Master Albert, but is soundly defeated, although not before mentioning that they cannot live in a world of light if they are born in the shadow of Albert.

When Grey or Ashe copy his DNA, they are able to use Bifrost's biting, and wheel-saw attacks. They can also launch his teeth as projectiles by holding down the attack button before a chomp, and use the open jaw as a nigh-impenetrable shield. The player can also attack foes by simply leaping on top of them, or simply turning away to thrash an unfortunate foe with his tail. Many small-to-medium size victims will be instantly destroyed by a tail-thrash attack, and thrown back into other enemies who will most likely also be destroyed. Despite all his attack capabilities, his biggest threat as a boss becomes his greatest weakness as the player's ally. His sheer size and slow movements make him a huge and easy target, almost completely negating any usefulness he may have ever had.

Trivia

 * His name is possibly a pun on the words "frost", and "bifurcation"; which means "to cut something in half".
 * In Norse mythology Bifrost is Rainbow bridge that leads from Valhalla to Midgard.