Updated list of characters requested on the poll. And yes they finally added Ridley to this list! Sora’s mentioned, but to point out Sora did appear on the Gameboy Kingdom Hearts game Chain of Memories in 2004. Special thanks to LostArfofRock of Gamefaqs for the list once again!
Hammer Bros. (Super Mario Bros. - 1985)
Toad (Super Mario Bros. 2 - 1988)
Geno (Super Mario RPG: Legend of the Seven Stars - 1996)
Link (The Legend of Zelda: The Wind Waker - 2002)
Ganon/Ganondorf (The Legend of Zelda/The Legend of Zelda: Ocarina of Time - 1986/1998)
Ridley (Metroid - 1986)
Diddy Kong & Dixie Kong (Donkey Kong Country/Donkey Kong Country 2: Diddy Kong’s Quest - 1994/1995)
King K. Rool (Donkey Kong Country - 1994)
Ninten (Mother - 1989)
Jeff (Mother 2/“Earthbound” in the U.S. - 1994/1995)
Claus (Mother 3 - 2006)
Lucas (Mother 3 - 2006)
Lololo and Lalala (Kirby’s Dreamland - 1992)
King Dedede (Kirby’s Dreamland - 1992)
Oguma (Fire Emblem: Ankoku Ryuu to Hikari no Tsurugi - 1990)
Sigurd (Fire Emblem: Seisen no Keifu - 1996)
Ike (Fire Emblem: Path of Radiance - 2005)
The Black Knight (Fire Emblem: Path of Radiance - 2005)
Black Shadow (F-Zero X - 1998)
Little Mac (Punch-Out!! Featuring Mr. Dream - 1990)
Dragon Chan (Super Punch-Out!! - 1994)
Ray 01 (Custom Robo - 2004)
Captain Olimar (Pikmin - 2001)
Lip (Panel de Pon - 1995)
Takamaru (Nazo no Murasamejou - 1986)
Sukapon (Joy Mech Fight - 1993)
Professor Kawashima (Brain Age: Train Your Brain in Minutes a Day - 2006)
#111 Possibly “Cat-Eye Link?”
#145 Possibly “Zehi New Ogre?”
#147 Unknown
#149 Unknown
Third Party Suggestions
Mega Man (Capcom) (Mega Man - 1987)
G-Red (Capcom) (Gotcha Force - 2003)
Simon Belmont (Konami) (Castlevania - 1986)
Colonel Yevgeny Borisovitch Volgin (Konami) (Metal Gear Solid 3: Snake Eater - 2004)
Lupus (Rare) (Jet Force Gemini - 1999)
Sora (Square Enix, Inc.) (Kingdom Hearts - 2002)
Princess Katia (From Software) (Lost Kingdoms - 2002)
Kalas (tri-Crescendo/Monolith Soft) (Baten Kaitos: Eternal Wings and the Lost Ocean - 2003)
A post from Bunnyflip of Gamefaqs clearing up some of the unknown stuff.
#111 Possibly “Cat-Eye Link?”
#145 Possibly “Zehi New Ogre?”
#147 Unknown
#149 Unknown
"Cat-eye Link probably refers to Wind Waker Link, who had cat like eyes (esp. in the original trailer/screens of the game).
#145 actually refers to Shin Oni Ga Shima; that games main antagonist was a female ogre if I’m not mistaken. If you’re wondering, Shin Oni Ga Shima is that crazy text-adventure game for NES/SNES with Donbe and Hikari. (there were a few other “Musashi Bananshi” games, or text-adventure titles, Nintendo made too, but I guess that’s the most popular one, next to Famicom Detective Club)
#147 is asking for music from Top Gear; not a character at all 
#149 is also asking for random stuff. I think he mentions character intros (he allues to Ness appearing in a flash of fire), and he wants a pinball stage, or something like that. Cool ideas, but no characters again 
Actually, 149 talks about something really cool: Kirby’s Animal Friends! I missed it the first time, but saw someone else mention it, and now I see it too. The writer suggests that characters and ride Rick, Kine, Koo, Nago, Pitch, and Chuchu just like the Kirby games, and they pop out of crates like enemies sometimes do 
The other letters are similar. One imagines a funny scene with Snake using Pokeballs, and another talks about how great the score is going to be. The last letter talks about online, and how Mario Kart DS kept records on your Wi-Fi detials."