Shy Guys are members from the Koopa Troop. Their most notable feature is their mask which obscures their face.
The Shy Guy Squad is a special attack appearing in Mario & Luigi: Bowser's Inside Story. This attack is gained in the Bowser Path, near the end. When the attack is used, a group of Shy Guys come onto the screen as Bowser rolls into his Spike Ball. The shy guys pull out a long rope, and the player has to repeatedly move the stylus over Bowser towards the right of the screen to pull him and the rope back. After a set amount of time, in which hopefully the player pulls the rope back a great deal, the rope will snap back into place, rocketing Bowser toward the enemy in the process. Bowser uses this move against Mario and Luigi during the boss fight against him, they must use their hammers to hit Bowser back at the Shy Guys. He won't use this attack if Bowser did not free his Shy Guy military forces when playing as him.
- In the Shy Guy Squad attack, Bowser rolls up into his Spike Ball. This is strange, as the spike ball is obtained much later in the game, at Peach's Castle.
- Mario and Luigi can talk to the Shy Guys before Bowser rescues them. They will regconize Mario, but don't regconize Luigi, who they think he is a Mario clone.