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.