try searching for it if you are trying to make a 2.5D game then i dont know what to say, i tried to look for some for u but i couldnt find any, on the other hand, if you want to make a regular 2D game i highly suggest the sonic sprites from the GBA series, sonic advance, SA2, SA3, sonic battle would possibly be the best because the games uses sprites that face in all four directions and there are a lot more characters.. i'm using them for a project i'm working on called: Sonic the Hedgehog: The Doom Egg. But yeah. i hope this was a help to you.
and here is a link to sonic battle sprites for ya!
http://www.spriters-resource.com/gameboy_advance/sonicbattle/ (this page also includes text, story images, etc.) Good luck!