Boom Boo, ブー, is a ghost that appears in several haunted stages of Sonic Adventure 2. It looks like giant versions of Boo normal type and only has one attack, which is to slowly move towards the character when in sight. Hitting them once will reduce their size, to a larger version of Boo attack type and another hit will make them Boo attack types completely. Therefore they take three hits to disappear and award 300 points. It should be noted that throwing objects doesn't affect ghosts.
|Normal mode||Hard mode|
|Knuckles||Death Chamber||Pumpkin Hill, Aquatic Mine, Death Chamber|
|Sonic Adventure 2|