Luigi's Mansion: Dark Moon [3DS]
Capturing Boos are introduced as early as Gloomy Manor's "Visual Tricks" mission. However, the game does not explicitly tell you what is the reward for capturing them all.
Gradual Infiltration - Capture all 5 Boos in "Gloomy Manor"
Hostile Intrusion - Capture all 5 Boos in "Haunted Towers"
Outlandish Interruption - Capture all 5 Boos in "Old Clockworks"
Severe Infestation - Capture all 3 Boos in "Secret Mine"
Terrifying Invasion - Capture all 5 Boos in "Treacherous Mansion"
#1 - Complete the Dark Moon Quest mode.
#2 - Obtain a 3 star rank on every mission in the Dark Moon Quest mode.
#3 - Collect every type of ghost in game. (Both Evershade Valley and
Beat the single-player campaign, then select the Scarescraper option from E. Gadd's bunker to unlock this mode.
Collecting all of a mansion's gems will unlock a statue that can be seen in the vault's gem collections.
Luigi statue - Collect all the gems in the Gloomy Manor.
Endless Floors in the Scarescraper
This option creates a Scarescraper with infinite floors as well as its own difficulty, also named "Endless".
Hunter Endless - Beat a Hunter mode in a 25F Scarescraper, then "Create a Scarescraper".
Polterpup Endless - Beat a Polterpup mode in a 25F Scarescraper, then "Create a Scarescraper".
Rush Endless - Beat a Rush mode in a 25F Scarescraper, then "Create a Scarescraper".
Surprise Endless - Beat a Surprise mode in a 25F Scarescraper, then "Create a Scarescraper".
Beat the mission "Visual Tricks" in Gloomy Manor