Boo Crew

Boo Crews, originally known as simply Boo Buddies, are Boos formed in large groups.

Super Mario World
In Super Mario World, Boo Crews are found only in the Donut Ghost House and Forest Ghost House. The cloud of Boos is usually transparent, which is when they are harmless, but individual ones will periodically turn opaque, which is when they are dangerous, to dive at Mario. They are indestructible and can only be avoided by the player.

Mario Kart series
Boo Crews appear in the Ghost Valley courses in Super Mario Kart, Mario Kart Wii and Mario Kart Tour, Banshee Boardwalk in Mario Kart 64 and Mario Kart DS, and Luigi's Mansion in Mario Kart DS, Mario Kart 7 and Mario Kart Tour. However, the Boos do not hurt the players.

Paper Mario: Sticker Star
A Boo Crew reappears in the Enigmansion in Paper Mario: Sticker Star.

Puzzle & Dragons: Super Mario Bros. Edition
Boo Crews appear as named in Puzzle & Dragons: Super Mario Bros. Edition as allies with a Dark attribute and sub-attribute. Their skill is "Boo Trick", which lets the player be able to move any orbs anywhere for 6 seconds except in Score Attack, while their awoken skill, "Twin Target", raises their attack and damages two opponents for each attribute the player clears four orbs.