Bubble Crab is a Maverick created by Sigma in Mega Man X2 designed to be based on a crab. He served on the sixth naval as a Maverick Hunter, along with Wheel Gator.
It could be too difficult to beat Bubble Crab without his weakness. The falling tide in the room could make it difficult if Mega Man X never prepares. Also, in the air when high above him, Crab will begin to jump upwards with his claws, as this could be a threat. When Crab makes the tide high enough, X could lock him by jumping over him and back firing when he lands and then repeats again. If X does that correctly, Bubble Crab will cancel a different weapon.
Bubble Crab only appeared in the mangas, Rockman X, Rockman Remix and Rockman X Mega Mission.
His level music appears in Mega Man X5 Collection, as Duffy McWhalen's stage theme.
On the artwork, you can see the Maverick logo on him. On his sprite, you can't see the whole logo.