While going through Booster's Tower, a switch can be found to open a new area of Booster Pass. After beating Booster Tower and returning to explore Booster Pass' hidden area, there will be a number of enemies called Apprentice. If Mario loses to an Apprentice, a cutscene will play after the Game Over screen of the Apprentice happily cheering that it will become Snifit #4, the 4th bodyguard to Booster. Revisiting Booster Tower after this will reveal a 4th bodyguard (the Apprentice that beat Mario). This can be repeated 8 times, where the 8th victorious Apprentice will be relocated to Grate Guy's Casino as there is no room for an 8th Snifit and Apprentices will no longer spawn in Booster Pass.
Contributed by KidDivinegon