Had a game boy phase and did this, used the pokemon sgb palette to get things started and then painted them using the NES palette.

Left to right, top to bottom: link, megaman, samurai Jack, braixen (Pokemon), tangle (Sonic idw comic), fat Larry (vampire tmb), Isaac (binding of Isaac), rayman, Jack Frost (shin megami Tensei), roll (megaman legends), GIR (invader Zim), donkey kong, Garcian Smith (killer7), Sundown (live a live), Mario, Kratos, raidou kuzunoha (Devil Summoner), Deadpool, videogamedunkey, Johnny bravo, Kamen Rider Knight, shantae,, Twitch (League of Legends), shovel Knight, mayor Armstrong (fma), lancer (deltarune), the traveler (journey), Dexter, Wilson (Don't starve), Nash (Street fighter) and 3-D Cowboy (God hates astronauts)