This thread is effectively a compendium of Luigi tech:
http://smashboards.com/threads/luigi-trials-video.347163/
• Autoland on platform by using an up aerial while inside of it [I'll edit this with a video example]
• Chain throws
• Dash forwards out of a backwards wavedash (to stay in place and stall, useful when wavedashing backwards to the ledge)
• Double aerials
• Edge cancels (of aerials, Super Jump Punch, Green Missile)
• Guaranteed combos and setups
• Interrupting a dash with a shield
• Ledgedash
• Ledge tech
• Pivot grab
• Pivot forward smash
• Platform drop cancelled nair
• Platform warp (
http://smashboards.com/threads/new-tech.308463/)
• Rising tornado
• Shield drop
• SHFFLed aerials (on hitting the opponent as well as just around the stage)
• Stopping or delaying your momentum carrying you offstage when wavedashing to the ledge; by jabbing, spotdodging, etc. [I'll edit this with a video example]
• Super tornado (apparently not practically useful but you should know it anyway;
http://smashboards.com/threads/super-tornado.304128/)
• Tornado from ledge (like ledgedashing but with a tornado instead of an airdodge)
• Turnaround fireball
• Vududash
• Walk forwards out of a backwards wavedash
• Wavedash out of dash dance
• Wavedash out of shield
• Waveland aerials