Bubble Man:

He is the first aquatic Robot Master created by Dr. Wily for underwater combat. However, a defect in his system makes him unable to walk underwater, being only able to move by jumping. After seeing this, Wily couldn't help but laugh at his way of moving. Despite this flaw, Bubble Man is able to swim.
Bubble Man attacks with normal shots from his arm cannon, and can shoot Bubble Lead shots from his arm cannon and the gun on the top of his head. Bubble Lead are durable bubbles that can be used for several purposes, like hitting opponents with small bubbles, wrapping opponents inside large bubbles, or protecting Bubble Man himself.