Nintendo of America revised its release schedule for the first half of 1999, including a few surprises. Super Smash Bros. (the new title for what has been commonly referred to as Smash Brothers) will be released on April 26. The first Pokemon game on the N64 appears to be Pokemon Snap (June 28), a game where you travel around an overworld taking pictures of various Pokemon. Rumors still indicate that Pokemon Stadium will be coming to the US before Snap, but Nintendo has not announced a date for that yet.
Game Boy Color will see some action in early May as well, with the release of several new colors to the mix, including berry (magenta), kiwi (lime), and dandelion (yellow).
Some additional release dates have been changed. Here's the new full schedule. Tetris 64 is off the list for now, but Nintendo's web site still lists The New Tetris as an April release.
Nintendo 64 April 26 - Super Smash Bros. May 10 - Ken Griffey Jr. Baseball 2 May 24 - Star Wars: Episode 1 June 14 - Jet Force Gemini June 28 - Command & Conquer June 28 - Pokemon Snap
Game Boy April 26 - Conker's Pocket Tales May 10 - Game Boy Color - New Housing May 10 - Griffey Baseball 2 May 10 - Super Mario Bros. Deluxe June 28 - Bass Fishing June 28 - Pokemon Pinball June 28 - R-Type DX