This is the info gathered from the Super Smash Bros. Direct.
Release Date (Window): 3DS version- Summer 2014, Wii U version- Winter 2014
- 3DS version runs at 60fps in 3D
- some assist trophies will run at 30fps
- fighter lineup the same between both games, but the stages will be different
- in the 3DS version, each stage has 2 songs tied to it
- in the Wii U version, visit My Music to play songs from past Smash games
- past stages returning in both versions
- Dr. Wily castle stage has the Yellow Devil attack the fighters at random times. The last person to get the final hit on the Yellow Devil will net them a massive explosion attack hurting all other players.
- boss characters appear in other stages as well
- Both versions of the game will have online play
- For Fun and For Glory online play modes when not playing with friends. For Fun includes random stage (except Final Destination) and items. You can also set parameters as you choose. Number of victories will be recorded. For Glory only lets you play only Final Destination. No items will be available here either.

- online play will now show Nintendo Network IDs. Online play will try to combat people that try to drop out of matches and may even ban them.

- online play will have a scoring competition. This will include scores for solo modes. This is called Global Smash Power. The larger the number, the better the player. This is compared to players worldwide. No rankings for online multiplayer, but matchmaking based on skill levels.

- Almost every stage has a Final Destination form
- There is a Master Ball item that summons rare and Legendary Pokémon. Arceus is confirmed as one of them.
- Samus' suit will no longer fall off after her Final Smash. Zero Suit Samus is still included on the roster, though. She now has jet boots.
- Zelda now has a Phantom Slash move that brings in a guard from Phantom Hourglass. Sheik also returns with burst grenade and bouncing fish moves.
- Kirby now has a Hammer Flip attack and an Ultra Sword final smash.
- King Dedede no longer throws Waddle Dees. He hits Gordos at you now.
- Lucario's aura attack has been strengthened. He also has a Mega Evolution
- Olimar can only have 3 Pikmin following him. Olimar now plucks Pikmin in a fixed order. He now uses winged Pikmin for his recovery jump.
- Pit has had the glide move removed. Three sacred treasures as the final smash
- Yoshi is returning and now stands more upright
- Rosalina can shoot out the Luma and control it separately, if wanted. They each have a different set of moves. She has a Star Bits move, a launch star long distance move, a gravitational pull that draws in items and blocks enemy shots, and a power star final smash.
- Little Mac has a Smash Attack that has megaton levels, but he is very weak in the air. He also has a terrible recovery ability. His power meter is filled up by other landed punches. It even gets filled when he gets hit by other attacks. The meter fills to a KO uppercut, a one-hit kill punch. Transforms into Giga Mac as a final smash. Wireframe Mac is an alternate costume. Punches called Straight Lunge, Joly Haymaker, Rising Uppercut, Slip Counter
- Villager moves include Pocket, Lloid Rocket, Balloon Trip, Timber and Dream Home
- Mega Man's final smash brings in multiple version of Mega Man over the ages to combine for a mega blast. Moves include Charge Shot, Spark Shock, Flame Blast, Flame Sword, Slash Claw, Air Shooter, Hard Knuckle, Super Arm, Metal Blade, Crash Bomber, Leaf Shield, Rush Coil.
- Wii Fit Trainer can use the sun salutation and store it up. She can also use deep breathing to strengthen. Both male/female versions are available and both are the same power level.
- custom move sets allowed online with friends or local, but not online with strangers
Smash Run is a 3DS-only mode in Smash Bros. 3DS. It's a 4-player battle game where you search a dungeon for power-ups. Has a time limit of 5 minutes. Each type of power-up has its on effects and give new strengths. After the 5 minutes are up, a battle takes place between the 4 players. You can enter this mode by choosing what power-ups you want from your collection. Features enemies from all sorts of game series'. Has a random fighter option as well.
^It's like City Trial in Kirby Air Ride.
- Charizard and Greninja will also be playable characters
I'm pretty sure that was it. I didn't get done watching it until a few minutes ago.