He will shoot bubbles from its mouth that can be deadly. If they touch the player they will stun you for a few seconds and they can also block part of a bomb's radius. He can also use his claws to put out the fuse on a bomb as well. He has to be damaged from the side or behind but be careful not to get crushed. When the player is beside him on either side, Grub Robs will look at the player with an angered expression, showing from his yellow anger vein, and charge at them.
After several hits he will take on his second form. He moves faster and shoot bubbles in all directions every few seconds. After a few more hits he will be defeated.
He once again reappears as the Area 3 boss in the Nintendo DS game Bomberman.