Super Mario Bros. Wii (including collecting all of the star coins) is really pretty easy, but nonetheless still a great solid addition to the smb platformers. When playing it I couldn't get over how similar the graphics were to super mario world for snes.
I'm talking about playing that TMNT when I was probably 4 or 5 years old and I haven't played it since. I know it's a common game, but it hasn't really showed up in any lots of NES games and I haven't felt like buying it individually. I'm sure now I could figure it out after a few tries.