No way. The GBA has a secondary 8-bit processor, but I don't think it has an NES emulator.
SMB is the only SMB game in AC, but there are plenty more NES games, including Donkey Kong and Mario Bros. (Yes, you can get Mario Bros. with an e-Reader.)
And yeah, Mario Master, you should read through Animal Crossing help. It'll tell you what's up with the game, and quickly.
You can be silent and let the world think you are a fool, or you can open your mouth and remove all doubt.