So.
Here's a challenge.
Add two newcomers from every Nintendo console/handheld (barring Virtual Boy). Then add two newcomers who debuted on a non Nintendo system.
Go!
Assuming that we aren't counting Game & Watch (Mr. Game & Watch covers most of the 47 games on there)...
NES: Ridley (Metroid) and Mike Jones (Star Tropics)
Game Boy (Colour): Dark Matter (Kirby's Dream Land 2) and Captain Syrup (Wario Land)
Super NES: K. Rool (Donkey Kong Country) and Terra Branford (Final Fantasy VI)
Nintendo 64: Saki (Sin & Punishment) and Ray (Custom Robo) (if Rare characters were an option, I'd add Banjo-Kazooie instead of one of them)
Gamecube: Alexandra Roivas (Eternal Darkness) and Krystal (Star Fox Adventures)
Game Boy Advance: Isaac (Golden Sun) and Vaati (Zelda: Four Swords)
Wii: Travis Touchdown (No More Heroes) and Midna (Zelda: Twilight Princess)
DS: Sylux (Metroid Prime Hunters) and Weavile (Pokemon Diamond/Pearl)
Wii U: Inkling (Splatoon) and Wonder Red (the Wonderful 101)
3DS: Dillon (Dillon's Rolling Western) and Buzzwole (Pokemon Sun)
Switch: Ribbon Girl (ARMS) and Rex/Pyra (Xenoblade Chronicles 2)
Non-Nintendo: Dante (Devil May Cry - PS2) and Doomguy (Doom - PC)
I really struggled for the portable systems. Still, I'm surprised that I mostly came up with Nintendo characters, with only four third party picks.