ITT: list most unforgiving Characters unlock requirements:

3D Player 2004

Your local Luigi, Daisy, Yoshi, and Diddy Kong fan
Banned User
and hope there are none like that in Smash 4. [Not time consuming ones]

Smash 64:
Captain Falcon: Clear 1-Player Game in 20 minutes or less.
Ness: Clear 1-Player Game on normal difficulty with 3 lives without continuing.

Ironically these 2 were the ones available from the start in Melee.

Melee:
Falco: Completing the 100-Man Melee
Pichu: Completing Event #37--Legendary Pokémon
Mr Game and Watch [only because other characters are hard]: Completing Classic, Adventure, or Target Smash with the other 24 characters

Brawl:
Because of how easy SSE is, you don't really have to do near-impossible tasks to unlock characters. In addition, much of the game has been made substantially easier including Multi-Man Melee, now Multi-Man Brawl and the events due to modifiable difficulty.
 
Captain Falcon is easy if you're playing in Very Easy Difficulty
Ness is easy because computers in Super Smash Bros. are awful

Falco, isn't hard either.
Neither is Pichu. Actually, Event #37 is actually one of my favorite events in the game
Mr. Game & Watch isn't hard.

Mewtwo is the most tedious.
 
Even without the DK technique it's still easy to beat

It's not like 15 minute Melee or anything
 
Since when is Pichu unlocked by clearing Legendary Pokémon?

I always did 200 battles to unlock Pichu.
 
 
....I'm sorry, was there supposed to be something in those spoilers?
 
Vommack said:
....I'm sorry, was there supposed to be something in those spoilers?

yes, I made an error and was in a process of fixing it.
 
3D Player 2004 said:
GalacticPetey said:
>Go to 100 man melee
>Select DK
>Spam down B
>Get hit by an unlucky Bob-omb
no Falco.
fixed

Because that happens every time you play 100 man melee, right?