Well thanks to fcgamer and Qiezei, it looks like I've got Mario 4, Mario 8, Sonic 5, Sonic 6 and Sonic 7 on the way! Thanks to everyone!
Now I'm just on the hunt for Super Mario Special 3, Sonic 8 and Donkey Kong 5: The Journey of Over Time and Space...
I thought I might share with you guys some covers I made for my game collection for these games. Over at The CoverProject.net, we discovered recently that the space above the card slot on Nintendo's 3DS cases were perfect for holding GB, GBC and GBA games. With two strips of foam (or something else), you can easily store them in protective cases without them sliding around, and manuals fit perfectly!
So I went ahead and made some unique covers for Mario 4 and Sonic 5-8. You guys' BootlegWiki was a big help there. I mostly created totally custom covers, although I did reference the original boxes for Mario 4 and Sonic 6.
You can download them here if you're interested in using them:
https://www.box.com/s/v7fq99l3f68e8mrlv6tw