VGFacts

Super Smash Bros.:

In SSB 64 the starting eight characters are placed in the order of when they first appeared in their respective titles on the character selection screen, starting with the oldest, Mario and Donkey Kong, and leading to the most recent, Pikachu.

Also in SSB 64, Masahiro Sakurai stated that final smashes were to be implemented, but the Nintendo 64 could not achieve this. Sakurai recorded voices such as, Ness saying, “PK Starstorm!” and Captain Falcon saying, “Come on!” Many other voices were also recorded.

A magazine, Electronic Gaming Monthly, stated that Sonic and Tails were unlockable in Melee. The magazine stated you had to defeat 20 enemies in Cruel Melee. This was easily proved fake, but some fans fell for it.

Also, a small website stated that Toad was unlockable in Melee. They had strategies on how to unlock him and fake screenshots. This was proved fake by the many mistakes that the website made.



Did you know that in Super Smash Bros Melee, Captain Falcons' red costume was originally planned to have a "Blood Falcon" emblem on his back, and was originally planned to say "Hell Hawk"?


Did you know that in Super Smash Bros Brawl, multiple unused character data files were found in the disc? These include:"dixie ,"dr_mario", "mewtwo, "roy","Pra_Mai","toon_sheik", and"toon_zelda".

Did you know that in Super Smash Bros Brawl, Pokemon Trainer has an unused jumping animation? This may hint that he was originally a planned to be a playable/separate character.


Did you know that in Super Smash Bros Brawl, in the text data for enemy names, a few unused names exist, implying enemies that were cut? These names include:
Melorin
Mechaboom
Bublit
Blowm
Plowm
Aliians
Aliian
And Mizzo, even though they can be found in the background for the Battleship Halberd.

Sources:
http://www.ssbwiki.com/Beta_elements
http://www.ssbwiki.com/Super_Smash_Bros.
http://www.ssbwiki.com/Beta_elements
http://www.ssbwiki.com/Rumors

I wouldn't bother including the stuff about lies from other people... They aren't really trivia.

Also, I wouldn't assume Pokémon Trainer was going to be a separate character or playable or whatever, but rather that he might have to jump up onto platforms in the background at times to be visible.

Yeah, leaping to other platforms through the stage is much more likely.