Instead of adding screenshots for each game, I'm posting the presentation for those who missed it. Below you can find a brief summary of the presented news - each section is a summary of NeoSeeker articles about the games in question.
Mario Golf: World Tour
Spoiler
The game will feature two "communities" and the "Friend Community" and the "Theme Community". These will allow players to pick special themes for courses or some extra special powers in Multiplayer.
Release Date: Summer
Mario Party 3DS
Spoiler
The game will feature seven game boards with exclusive games. Those includes a board all about stealing cards from other players, a spaceship board where you can use boots and a stage where bullets can knock you back. Unfortunately, no Multiplayer features were shows so-far.
Release Date: Winter
New Super Luigi U
Spoiler
This DLC pack for New Super Mario Bros. U changes the game and allows to play it as Luigi. The overworld remains unchanged, but all 82 stages modified. Luigi controls differently than Mario - he can jump higher and doesn't stop as easily after dashing. Each level within Luigi's adventure will have a 100 second timer.
Release Date: Summer
Mario & Luigi: Dream Team
Spoiler
Princess Peach has been kidnapped again after Luigi fell asleep on a mysterious pillow. Princess Peach was sucked into a portal formed from his dream. Mario will have to use an assortment of special powers bestowed upon him by Luigi's dreams to rescue her. Mario can interact with Luigi using the bottom screen what in turn creates effects on the top one - for example, tugging Luigi's moustache may you into the air.
Release Date: August 11th in North America, Japan will receive a special 3DS LL bundle
Donkey Kong Returns 3D
Spoiler
The remake will will include eight new levels, they can be played after finishing the original game.
Release Date: May 24th
Yoshi's Island Sequel 3DS
Spoiler
A new Yoshi's Island title was announced today during the event. It will feature all of the classic Yoshi's Island features, such as hover jumps, coin collecting and egg throwing.
Mario and Donkey Kong: Mini's on the Move
Spoiler
Another installment in the Mario and Donkey Kong puzzle franchise is in the works. Players will be able to upload and download their ownlevels, the game will also include over 180 stages and four types of mini-games.
Release Date: May 9th
Pikmin 3
Spoiler
The game brings a new species of Pikmin that can fly. The critters were shown lifting objects and carrying them across water.
Release Date: August 4th
Earthbound (WiiU VC)
Spoiler
The Nintendo classic will be coming to the Virtual Console by the end of the year.
Game & Wario
Spoiler
The new installment in the minigame-oriented Wario franchise.
Release Date: June 23rd
Monster Hunter 3 Ultimate
Spoiler
The game received a patch allowing Multiplayer
Lego City Undercover (Prequel)
Spoiler
The 3DS prequel of the game will soon be released.
Release Date: April 21st
Animal Crossing: New Leaf
Spoiler
The game will be getting a Nintendo 3DS XL bundle in which the game will be pre-downloaded. Price? $219.99.
Release Date: June 9th
Bravely Default: Flying Fairy and Professor Layton and the Azran Chronicles
Spoiler
The games now have confirmed localizations.
Release Dates: 2014
Shin Megami Tensei IV
Spoiler
The game will come with a music CD, a strategy guide and a collectible case. This 100+ hours long adventure and all the goodies are going to cost you $50.
Release Date: July 16th
Starship Damrey, Keiji Inafune's Bugs vs. Tanks! and Attack of the Friday Monsters!
Spoiler
Games will be localized, no further info available.