A crippling addiction comes to light, and a popular Nintendo series appears in double.
A title I'd really like to be able to play on-the-go is Pokémon Puzzle Challenge, originally released on Game Boy Color (and similarly on Nintendo 64 as Pokémon Puzzle League). I've chosen this over Tetris Attack as it has saving capability rather than passwords, it's more colourful, and it includes an additional Garbage Mode, and Super Hard and Intense difficulties, turning the CPU into an impossibly fast tyrant who throws the largest possible, most-difficult-to-clear garbage blocks at you within seconds of starting a round. At least you get to hear the combo sound often.
While the Nintendo DS has Planet Puzzle League, it just doesn't feel the same. The stylus controls only slow things down. The sound effects are also far less satisfying than the click, click, clicking away of the Pokémon-themed version. The story mode of the Pokémon variety is a superficial layer that has no effect on gameplay. Battling trainers unlocks more Pokémon to play as, and playing through the story mode will take you through battles with the various trainers and gym leaders in the region. However, the absence of a story mode does leave Planet Puzzle League lacking, since it takes a lot of motivation away as there's no sense of completion. All the levels are just there, waiting, at the start.
Panel de Pon is a game I never tire of (until I lose against the CPU 180 times in a row on the hardest difficulty). I own practically every version released, including the Japan-only Nintendo Puzzle Collection on GameCube. The ease of a portable, downloadable Virtual Console version would mean that yes, I would add yet another version to my collection to feed my Panel de Pon addiction.
My second choice game is the Legend of Zelda: Oracle of Ages/Seasons. I've played them through several times myself, but I think they were overlooked and deserve another chance. The games are a blend of Link's Awakening and A Link to the Past in gameplay and story style, and have combat and puzzles that are on equal terms with both the Game Boy and SNES titles. Perhaps a reason they were overlooked is that development was done by Capcom's Flagship team rather than Nintendo. The game series was still supervised by Nintendo, and when the ambitious Triforce trilogy of games was deemed too complex, it was Shigeru Miyamoto who suggested it was scaled back to two games.
Nintendo later hired the director of these two titles, Flagship's Hidemaro Fujibayashi, after Capcom dissolved the developer. He has since joined Nintendo EAD where he co-directed Phantom Hourglass and is now directing the upcoming Skyward Sword.
Impressively, each game is a full handheld Zelda title and contains completely different overworlds and dungeons.
Oracle of Ages is said have more of a puzzle focus and Link travels into the past to overcome the overworld's obstacles and avert the fate of the Maku Tree. It's not unlike A Link to the Past's Light World and Dark World. I wouldn't put too much weight on the puzzle/combat comparison though, since Oracle of Seasons is said to be the combat focused of the two, yet it also gives you the underground world of Subrosia, home of quirky characters closer to those of Link's Awakening than any other title. In Subrosia, you'll spend more time digging at the beach and dancing than encountering anything dangerous.
After you complete either game, you're presented with a password to start the next game with. This changes the game by giving you additional passwords to unlock rings in each game for your collection and changing the placement of some items. The story also incorporates characters from the other game, as well as presenting the true, final ending. Having both of these titles in digital form would give quick and easy access to the password-unlock features as you would never have to switch out a cartridge.