|Mega Man jumping up to attack Octobulb while illuminated.|
Octobulb is only vulnerable when it is illuminated, which occurs by charging electricity via running on one of the two treadmills in its lair. This causes four platforms to appear which can be used to jump on and reach the lit bulb. When its electricity runs out, it produces electric shocks which run back and forth along its wires. Octobulb also creates two small lightbulb-type enemies called Little Pachipachi (リトルパチパチ?), which follow the player during the fight. Defeating both enemies causes two more to be created.
On higher difficulties, the amount of time Octobulb remains lit up decreases. Multiple charges are needed in order to have time to shoot and destroy it.
Due to the amount of hits, Water Shield and Triple Blade work very well on most minibosses. Due to its size, a single well-timed and well-placed Commando Bomb can destroy it with a single hit.
Bass has the ability to fire straight up and negate the need for the platforms.