Puyo Puyo, Compile's series of falling-blob puzzle games, currently has two iterations on the American Virtual Console. Neither of these games contain the words "Puyo" or "Puyo" in their titles. But Kirby's Avalanche and Dr. Robotnik's Mean Bean Machine are Puyo through and through(yo). Which automatically means that they're cute and enjoyable Tetris/Columns-esque puzzle games. And (insert segue here) here are some codes for them.
Dr. Robotnik's Mean Bean Machine (GEN)
Skip to the final boss: Yes, it's weird that a puzzle game like this has level passwords. It's even weirder for it to have bosses. Should you want to experience the weirdness for yourself, you can take advantage of the fact that level passwords are delightfully easy to share on the Internet -- much more so than, say, save files. To access the final boss, enter the following password: for easy mode, enter Yellow, Has, Blue, Blue. For normal, enter Purple, Yellow, Has, Clear. Hard: Has, Clear, Purple, Has. Hardest: Red, Red, Clear, Yellow.
Kirby's Avalanche (SNES)
Custom options menu: Hold down all four face buttons on controller 2 during gameplay, then reset the game. Go into the options menu and more options will appear, including level select and a sound test. We cannot guarantee the utility of this code; in fact, it's a bit of a research interest for us. Does the soft reset of the Virtual Console work like a real reset? If this code works, it does!
[Codes via GameFAQs]