When I think of a retro rep in Smash, I think of a character from a discontinued franchise, from an old game that performed poorly sales-wise, from a forgotten game or franchise, etc. So I can't really agree when people suggest that Mega Man, Pac-Man and Little Mac are retro characters, because they are neither forgotten characters and their franchises still get games; Granted, Mega Man is possibly dead, but the franchise still got a few games in the past generation.
So the problem here is the term "retro". There should be a different term for characters like Ice Climbers and Pit. Yes, they are retro characters, but so are Mario, Link, Zelda, Samus, Pac-Man, Donkey Kong, etc. "Forgotten characters", maybe? Surely some people still remembered Ice Climbers and Pit before Melee and Brawl, respectively, but not really a lot of people. Heck, I started playing games on a NES, played games like Mega Man, Mario Bros 3 and I had no idea who the hell Ice Climbers and Pit were before seeing them in Smash Bros.
I was meaning to bring a point in a "retro" character-related thread and this seems to be a good opportunity: What if Sakurai decided to revive a character from a not-so-old-school game instead? Every time we speculate about the new Ice Climbers/Pit, we only bring up characters from NES, SNES and Game Boy games. What if Smash 4's Ice Climbers isn't an extremely old character, but a somewhat retro one from a Nintendo 64, Game Boy Advance or heck, even a Gamecube game?
This is a list of all the N64/GBA/GCN games that don't have playable characters in Smash.
Nintendo 64 games
Pilotwings 64 (Pilotwings stage is in SSB Wii U)
Wave Race 64
1080 Snowboarding
Custom Robo (Ray is an Assist Trophy in Brawl)
Doshin the Giant 1
Sim City 64 (Dr. Wright is still an Assist Trophy)
Shigesato Itoi's Bass Fishing No. 1 Final Edition
Excitebike 64 (Excitebikers is an Assist Trophy in Brawl)
Doshin the Giant: Chibikko-Chikko Kids
Custom Robo V2
Sin & Punishment: Successor of the Earth (Saki is still an Assist Trophy)
Game Boy Advance games
Kurukuru Kururin (Helirin is an Assist Trophy in Brawl)
Napoleon
Golden Sun (Isaac is an Assist Trophy in Brawl)
Advance Wars (Infantry & Tanks is an Assist Trophy in Brawl)
Play Anywhere: Yakuman Advance
Magical Vacation
Tomato Adventure
Tilting Puzzle: Happy Panechu!
Golden Sun: The Lost Age
Momoko Sakura's Exciting Carnival
Custom Robo GX
Legendary Starfy (Starfy is still an Assist Trophy)
Kururin Paradise
Advance Wars 2: Black Hole Rising
Legendary Starfy 2
Oriental Blue
Legendary Starfy 3
Game Boy Wars Advance 1+2
Play-Yan
Millennium Family
Dr. Mario & Puzzle League (only listed this because of Puzzle League)
Drill Dozer (Jill is an Assist Trophy in Brawl)
Polarium Advance
Eyeshield 21: Devilbats Devildays
Calciobit
bit Generations games
Rhythm Heaven (Gematsu leak says Chorus Men are in)
Gamecube games
Wave Race: Blue Storm
Cubivore: Survival of the Fittest
Doshin the Giant
Eternal Darkness: Sanity's Requiem
Nintendo Puzzle Collection (only listed it because of Panel de Pon)
Giftpia
1080 Avalanche
Custom Robo
Kururin Squash!
Chibi-Robo!
Geist
Battalion Wars
Legendary Quiz Tournament of Champions
Odama