Not to say that these people did it first in any way, its just I decided something was useful after watching them do it (in person or in a vid) and found ways to apply it... Some are really basic things I noticed when I just started.
SlashTalon (non-active falco) - down-b has rediculous range.
Kyle - F-air when coming from offstage while being edge-gaurded can catch some who don't expect it.
Famous - F-air infinite jump thing.
Will - Using up-b to run away and land on platforms on places like smashville/battlefield, up-b from the ledge to onstage works sometimes eventhough it looks like it shouldn't, and holding down before you jump makes it easy to not fast-fall when you d-air offstage. Also, switching between f-air and d-air for water spikes (use what's not stale last).
Ripple - side-b after ledge jump and OoS (Unexpected and can break a shield lol). I also learned you can run offstage and fair without jumping and still come back. I may have got using more up-b approaches from him too. Also the basics against IC and some ways to land grabs.
Cable - Sometimes spamming up angled f-tilt against MK psychologically makes them afraid to tornado.
Rag - Some ideas about the snake matchup, charge an u-smash after side-b (Though it still never works for me), Save smashes for kills.
F_T_S - Throwing out somewhat random non-charge punches seems to work.
Silfa - Up-b braking. I never did it and considered it useless until I saw it working for him in person.
Micealis - Some situations I could use u-smash
Chineseah (probly spelled wrong) - u-tilt is really good
Bum - Well spaced f-smashes can go a long way
Kadaj - Ideas on how to play DK on Japes.
Will/Cable - I suck offstage in DK dittos lol
There's more... I just don't feel like thinking much anymore.