It attacks by splitting into a series of bouncing purple projectiles that go across the screen before reforming on the other and shooting a sole projectile at the player.
During Desperation Mode, the Dark Devil gains a new attack wherein it will phase off screen and send body parts flying from both sides while also creating a wind effect, after this is done it will reform like normal.
- When the boss was first discovered, the English speaking fandom dubbed it the "Purple Devil" due to its purple colorization. The name "Dark Devil" comes from the game files. It is possible, given this Devil's main attack is based on bouncing projectiles, that the boss was inspired by Dark Moon from Mega Man V on the Game Boy.
- The attack with body parts flying from both sides of the screen is likely based on an attack the Shadow Devil used from Mega Man X5. In addition, the Dark Devil has the same light pattern around its eye.