I've been working on this for awhile, but it's finally finished. The definitive list of unused fighters in Smash. Everything is 100% quoted and sourced. Anything that I could not find an original source for, was put under, "Possible Misinformation".
Some new information:
Bowser and Dedede were worked on in 64
Wolf was probably not planned for Melee.
Wario was next in line for Melee
Sukapon was going to be an item in Melee
Additional information on the cut stages in Melee
Blastoise was briefly considered for the Pokemon Trainer in Brawl
My additional thoughts on the data that I found in Smash 4
Some new information:
Bowser and Dedede were worked on in 64
Wolf was probably not planned for Melee.
Wario was next in line for Melee
Sukapon was going to be an item in Melee
Additional information on the cut stages in Melee
Blastoise was briefly considered for the Pokemon Trainer in Brawl
My additional thoughts on the data that I found in Smash 4