In case you're interested, the screenshots featured in this wallpaper are of (from left to right, top to bottom):

Mario & Luigi ("The Super Mario Bros. Super Show!")
Ash, Misty & Brock ("Pokémon")
Diddy Kong ("Donkey Kong Country")
Peter Puppy ("Earthworm Jim")
Tiff ("Kirby: Right Back At Ya!")
Bokkun ("Sonic X")
Link, Zelda & Spryte ("The Super Mario Bros. Super Show!")
Antione ("Sonic the Hedgehog")
Pac-Man ("Pac-Man")
Kevin Keene ("Captain N: The Game Master")
Larry Koopa ("The Super Mario Bros. Super Show!")
Kirby ("Kirby: Right Back At Ya!")
Donkey Kong ("Donkey Kong Country")
Mega Man ("Mega Man")
Dr. Robotnik, Scratch & Grounder ("Adventures of Sonic the Hedgehog")
Yoshi ("The Super Mario Bros. Super Show!")
Giovanni ("Pokémon")
Butch & Cassidy ("Pokémon")
Snively ("Sonic the Hedgehog")
Leonardo & Michaelangelo ("Teenage Mutant Ninja Turtles")
Frogger ("Saturday Supercade")
Yugi Motou ("Yu-Gi-Oh!")
Raphael ("Teenage Mutant Ninja Turtles")
Q-Bert and his friends ("Saturday Supercade")
King Dedede & Escargoon ("Kirby: Right Back At Ya!")
Mega Man ("Captain N: The Game Master")
Kid Muscle ("Ultimate MUSCLE")
Earthworm Jim ("Earthworm Jim")
Meowth, Jessie & James ("Pokémon")
Sonic ("Sonic X")