Story – Luigi's Mansion™ 3 for the Nintendo Switch™ system – Story
Mario & Luigi Teams Up to Battle Final Boss in Luigi's Mansion 3 + Ending - YouTube
In the Luigi's Mansion 3 reveal trailer, there are pizza boxes that say "since 1983", which is the year Mario Bros. released and Luigi's first appearance. : r/GamingDetails
Luigi's Mansion 3: Story Summary & Ending Explained