The most relevant in competitive play is "shine," the down-special move of Fox and Falco. It's considered the best move in Melee. This term is much more accepted in the community because it implies its usage as an attack, rather than as a reflector (the official name).
Randall, the cloud from Melee Yoshi's Story, is considered the god of fate in competitive play. Expect to see a lot of incredible wins and defeats thanks to him.
Captain Falcon's KNEE OF JUSTICE!!!
Peach's vegetables are known as "turnips" in the competitive community.
Naturally, David Hayter, Christopher Randolph, Paul Eiding, Rob Paulsen and Kim Mai Guest reprising their Metal Gear Solid roles.
Lucas (and Pit in the English version) is voiced by Lani Minella, known as the current Ivy and the former (Pre-Shadow the Hedgehog) Rouge the Bat (the latter role makes it quite amusing considering Sonic's presence). Also Luke in the American dub of Professor Layton.
And if you at all find the announcer in Brawl's voice familiar, chances are you watched Bill Nye as a kid since that's Pat Cashman, announcer for Bill Nye and the Seattle-only Almost Live.
The voice over in the commercial for the original game (linked above) is none other than Mr. Movie Trailer himself, the late great Don LaFontaine.
Famously, Sakurai himself voiced King Dedede.
Zero Suit Samus is also the second Carmelita Fox, as well as Krystal. She's also famous for being the facial/body model for Alma Wade, Chell, and (the original) Zoey.
Meta Knight's Japanese voice actor is the same one as in the anime.
Marth Debuted in Smash Bros.: The Trope Namer. Marth's debut game (technically a remake thereof) did not appear in American and European markets until 2010, almost nine years after his first exposure to Western audiences. Lip's Stick also has yet to be seen in its natural habitat.
There were plans to include real time damage in Brawl as well, with characters looking noticeably damaged if they received too much of a beatdown. Captain Falcon's helmet would become chipped, and Meta Knight's mask would have started to crack.
Melee had Ditto as a Poké Ball Pokémon. It would copy the summoner and attack everyone else. It was taken out because it crashed the console.
