Mario (1) and NES Controller appear in the first and second Mural stages respectively. I have just reached a stage called "Nintendo Murals" which is all sprite art. So far there have been loads of Super Mario Bros. enemies, Link (1), Ice Climber and Balloon Fight. Will update with more as I unlock them!
Damn, finally into the near-impossible ones. Working on creating a few myself as well ;D
OK so, in no particular order...
Mario (2) (SMB) Mario (3) (SMB) Goomba (SMB) Spiny (SMB) Cheep Cheep (SMB) Piranha Plant (SMB) Bullet Bill (SMB) Koopa Troopa (SMB) Lakitu (SMB) Buzzy Beetle (SMB) Link (1) (The Legend of Zelda) Link (2) (The Legend of Zelda) Aquamentus (The Legend of Zelda) Fairy (The Legend of Zelda) Donkey Kong Jr. (Donkey Kong Jr.) Balloon Fighter (Balloon Fight) Ice Climber - Popo (Ice Climber) Red Excitebiker (Excitebike)
So yesterday I finally cleared all the main stages and watched the end credits. Then you unlock three more worlds, including... Bonus Nintendo Murals!
Link (3) - Zelda II: Adventure of Link Peach - Super Mario Bros. Koopa Paratroopa - Super Mario Bros. Pit - Kid Icarus Armos - The Legend of Zelda Princess Zelda - The Legend of Zelda Blue Excitebiker - Excitebike Stalfos - Zelda II: Adventure of Link Darknut - The Legend of Zelda Blooper - Super Mario Bros. Luigi - Super Mario Bros. Raccoon Mario - Super Mario Bros. 3 Boo - Super Mario Bros. 3 Samus Aran - Metroid Bowser - Super Mario Bros. Hammer Bro - Super Mario Bros. Thwomp - Super Mario Bros. 3 Urban Champion - Urban Champion
I ploughed through them all to bring you this information. I am still stuck on Urban Champion, so just one more reason to hate that damned game