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.

Appearance
Bifrost is a monstrous Pseudoroid based on a crocodile. He has a massive light blue body with red lights. His long head contrasts with his relatively compact torso, which is balanced by the thick limbs and tail. He has a number of ice spikes for claws and teeth.

Bifrost has a highly-developed AI, with primary function is stopping enemy advances, as opposed to destroying enemies, so he has been equipped with a wide-area effect freeze weapon, that delivers a rearward signal to block an enemy's path with the ice wall "Giga Freeze". . Bifrost is a slow Pseudoroid, 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, but he compensates for his lack of speed with his sheer strength and endurance; he can pulverize anything within reach with brute force. 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. Bifrost's tail is his weak point.

Fitting of his appearance, Bifrost has a savage personality, threatening to crush every last one of Mega Man Model A's bones with his jaws. However, he is still entirely loyal to Master Albert.

Mega Man ZX Advent
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. He awaits the rise of the Mega Man King and the new world so that the Mechaniloids will annihilate the "old-world inhabitants". 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.

Power and Abilities
Bifrost is encountered in a wide, partially submerged room with a breakable ice bridge. He tends to repeat a routine of walking forward with his jaw wide open, shooting his Ice Fangs before attempting an Ice Bite near the corner and leaping backwards to attack from a distance. His body is so heavy that the ground shakes when he lands, throwing the player off balance.

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.

Defeating Bifrost under specific conditions will award the player with Gold, Silver and Bronze medals. Collecting all 24 medals in the game will unlock Model a.
 * Ice Fang: Bifrost opens his maw wide, shooting a series of ice thorns at the player as he walks forward.
 * Ice Bite: Bifrost finishes the Ice Fang attack with a violent bite.
 * Crocod'wheel: Bifrost spits out a number of spiked wheels which roll across the floor and walls.

Defeating Bifrost under specific conditions will award the player with Gold, Silver and Bronze medals. Collecting all 24 medals in the game will unlock Model a.
 * Gold: Defeat Bifrost using only Model A's Homing Shot.
 * Silver: Fight Bifrost as Buckfire (A-Trans).
 * Bronze: Fight Bifrost as Queenbee (A-Trans).

Trivia

 * Bifrost is by far the largest Pseudoroid of Mega Man ZX Advent.
 * Bifrost is one of the three Pseudoroids who retained his original name in the English version. The others are Rospark the Floroid and Argoyle & Ugoyle the Shisaroids.
 * The Crocod'wheel attack functions similarly to Wheel Gator's Spin Wheel.
 * Bifrost has a secret attack that entails hitting an enemy with his tail as he turns around. It can be used via A-Trans.